Friday, April 24, 2009

Upgrading to Ubuntu 9.04 From 8.10 (Desktop)


Here is the tutorial for upgrading Ubuntu 8.10 (Intrepid Ibex) desktop to latest Ubuntu Linux 9.04 (Jaunty Jackalope) over the Internet.

Ubuntu Linux support direct upgrade Ubuntu 9.04 from Ubuntu 8.10.

Make sure you have all updates applied to Ubuntu 8.10 before you start upgrade. To do this visit:
System -> Administration -> Update Manager







Ubuntu Update Manager

Click on "Install Updates"

Network Upgrade for Ubuntu Desktops over the Network

You can easily upgrade over the network as follows:

Visit System > Administration > Update Manager




Click the Check button to check for new updates.

A message will appear informing you of the availability of the new release.

Click Upgrade.

Follow the on-screen instructions.

Upgrade Ubuntu Server 8.10 to 9.04

ubuntu logo

You can upgrade the server either from console or from network remotely.
Server
Be sure that you have all updates applied to Ubuntu 8.10 server before you upgrade. Type the following command to apply updates:
$ sudo apt-get update
$ sudo apt-get upgrade

WARNING! Backup important data, sql and configuration file before server running the following upgrade commands. The following discussion only applies to the SERVER edition. For Ubuntu 9.04 desktop upgrade click here.

Next, install update-manager-core if it is not already installed:
$ sudo apt-get install update-manager-core


Finally, start the upgrade tool, enter:

$ sudo do-release-upgrade


Now, just follow the on-screen instructions to upgrade your server over ssh session.

Thursday, April 23, 2009

Oracle buys Sun Microsystems



WASHINGTON - SOFTWARE developer Oracle has reached a US$5.6 billion(S$8.4 billion) deal to purchase Sun Microsystems, the two companies announced Monday in a joint communique.

'The acquisition of Sun transforms the IT industry, combining best-in-class enterprise software and mission-critical computing systems,' Oracle's chief executive Larry Ellison said in the statement.

'Oracle will be the only company that can engineer an integrated system - applications to disk - where all the pieces fit and work together so customers do not have to do it themselves,' he said.

'Our customers benefit as their systems integration costs go down while system performance, reliability and security go up.'

Sun chairman Scott McNealy hailed the merger as 'an industry-defining event.'

Company officials said Sun's board of directors have unanimously sanctioned the deal which is expected to close this summer pending approval from the company's stockholders and federal regulators.

Wednesday, April 22, 2009

Upgrade SuSE11.0 to SuSE11.1



Here are the three steps to do this with zypper (the command line package manager):


1. zypper update

Make sure your system is up to date

2. change repos

change all your repositories over to 11.1 recomend you just stick to oss non-oss and packman to avoid problems

3. upgrade

zypper dist-upgrade

Done, you should have now successfully upgraded your system to 11.1. You can check that with
cat /etc/SuSE-release

Analyze apache log with awk



Lets say we want to find the amount of times a specific ip address has hit your webserver,
on this example we are assuming your apache access_log is located in /usr/local/apache/logs

The full command would be:


awk '{print $1}' /usr/local/apache/logs/access.log | sort | uniq -c | sort -fr


and the output would be like this:

155 90.193.xx.xx
154 86.143.xx.xx
109 82.17.xx.xx
85 90.213.xx.xx
74 193.28.xx.xx

How to change the shell



The chsh command can be used to change your shell.

There are other options that may be used as well. To check the available shells on your system, use the following command:

chsh --list

which will produce a list similar to:

/bin/sh
/bin/bash
/sbin/nologin
/bin/ash
/bin/bsh
/bin/ksh
/usr/bin/ksh
/usr/bin/pdksh
/bin/tcsh
/bin/csh

To change the shell to csh, use the command:

chsh -s /bin/csh

To verify the current shell, use the command:

echo $SHELL

Note:
The above example is for the root user. Non-root users are prompted for their password before the shell is changed. These changes will take effect on the next login.

Tips for Cron



In addition to Crontab tutorial here is the post for tips on cron.


Use of operators


An operator allows you to specifying multiple values in a field. There are three operators:

1. The asterisk (*) : This operator specifies all possible values for a field. For example, an asterisk in the hour time field would be equivalent to every hour or an asterisk in the month field would be equivalent to every month.

2. The comma (,) : This operator specifies a list of values, for example: "1,5,10,15,20, 25".

3. The dash (-) : This operator specifies a range of values, for example: "5-15" days , which is equivalent to typing "5,6,7,8,9,....,13,14,15" using the comma operator.

Disabling Email output:

By default the output of a command or a script (if any produced), will be email to your local email account. To stop receiving email output from crontab you need to append >/dev/null 2>&1.

For example:

0 3 * * * /root/backup.sh >/dev/null 2>&1

To mail output to particluer email account let us say
rdx@nixtrix.co.cc you need to define MAILTO variable to your cron job:

MAILTO="rdx@nixtrix.co.cc"

0 3 * * * /root/backup.sh >/dev/null 2>&1

Task:

To list your crontab jobs use the command
type the following command:
# crontab -l

To remove or erase all crontab jobs use the command:
# crontab -r


Use special string to save time


Instead of the first five fields, you can use any one of eight special strings. It will not just save your time but it will improve readability.

Special string Meaning
@reboot Run once, at startup.
@yearly Run once a year, "0 0 1 1 *".
@annually (same as @yearly)
@monthly Run once a month, "0 0 1 * *".
@weekly Run once a week, "0 0 * * 0".
@daily Run once a day, "0 0 * * *".
@midnight (same as @daily)
@hourly Run once an hour, "0 * * * *".


Run ntpdate every hour:

@hourly /path/to/ntpdate

Make a backup everyday:


@daily /path/to/backup/script.sh

Understanding /etc/crontab file and /etc/cron.d/* directories

/etc/crontab is system crontabs file. Usually only used by root user or daemons to configure system wide jobs. All individual user must must use crontab command to install and edit their jobs as described above. /var/spool/cron/ or /var/cron/tabs/ is directory for personal user crontab files. It must be backup with users home directory.

Typical /etc/crontab file entries:

SHELL=/bin/bash
PATH=/sbin:/bin:/usr/sbin:/usr/bin
MAILTO=root
HOME=/

# run-parts
01 * * * * root run-parts /etc/cron.hourly
02 4 * * * root run-parts /etc/cron.daily
22 4 * * 0 root run-parts /etc/cron.weekly
42 4 1 * * root run-parts /etc/cron.monthly

Additionally, cron reads the files in /etc/cron.d/ directory. Usually system daemon such as sa-update or sysstat places their cronjob here. As a root user or superuser you can use following directories to configure cronjobs. You can directly drop your scripts here. run-parts command run scripts or programs in a directory via /etc/crontab

Directory Description
/etc/cron.d/ Put all scripts here and call them from /etc/crontab file.
/etc/cron.daily/ Run all scripts once a day
/etc/cron.hourly/ Run all scripts once an hour
/etc/cron.monthly/ Run all scripts once a month
/etc/cron.weekly/ Run all scripts once a week


Here is a sample shell script (clean.cache) to clean up cached files every 10 days. This script is directly created at /etc/cron.daliy/ directory i.e. create a file called /etc/cron.daily/clean.cache:

#!/bin/bash
CROOT="/tmp/cachelighttpd/"
DAYS=10
LUSER="lighttpd"
LGROUP="lighttpd"

# start cleaning
/usr/bin/find ${CROOT} -type f -mtime +${DAYS} | xargs -r /bin/rm

# if directory deleted by some other script just get it back
if [ ! -d $CROOT ]
then
/bin/mkdir -p $CROOT
/bin/chown ${LUSER}:${LGROUP} ${CROOT}
fi

Job Automation under Linux/Unix machines



Cron
jobs are used to schedule commands to be executed periodically i.e. to setup commands which will repeatedly run at a set time, you can use the cron jobs.


crontab is the command used to install, deinstall or list the tables used to drive the cron daemon in Vixie Cron. Each user can have their own crontab, and though these are files in /var/spool/cron/crontabs, they are not intended to be edited directly. You need to use crontab command for editing or setting up your own cron jobs.

To edit your crontab file, type the following command:
$ crontab -e

Syntax of crontab

Your cron job looks like as follows:
1 2 3 4 5 /path/to/command arg1 arg2

Where,

* 1: Minute (0-59)
* 2: Hours (0-23)
* 3: Day (0-31)
* 4: Month (0-12 [12 == December])
* 5: Day of the week(0-7 [7 or 0 == sunday])
* /path/to/command - Script or command name to schedule

Same above five fields structure can be easily remembered with following diagram:

* * * * * command to be executed
- - - - -
| | | | |
| | | | ----- Day of week (0 - 7) (Sunday=0 or 7)
| | | ------- Month (1 - 12)
| | --------- Day of month (1 - 31)
| ----------- Hour (0 - 23)
------------- Minute (0 - 59)


Example(s)
If you wished to have a script named /root/backup.sh run every day at 3am, my crontab entry would look like as follows:

(a) Install your cronjob:
# crontab -e

(b)Append following entry:
0 3 * * * /root/backup.sh

Run five minutes after midnight, every day:
5 0 * * * /path/to/command

Run at 2:15pm on the first of every month:
15 14 1 * * /path/to/command

Run at 10 pm on weekdays:
0 22 * * 1-5 /path/to/command

Run 23 minutes after midnigbt, 2am, 4am ..., everyday
:23 0-23/2 * * * /path/to/command

Run at 5 after 4 every sunday
:5 4 * * sun /path/to/command

logout - Linux Man Page

SYNTAX
logout [n]

Exit a login shell.

Returns a status of n to the shell's parent.

A login shell, is your topmost shell, and is started when you log in.

When you terminate a login shell (via the commands `exit', `logout,' or the end of file [^D]), you are logged out completely.

Sub-Shells

A `sub-shell' is a shell created after login, either by loading a new shell or opening a window with a graphics interface. A sub-shell usually will not accept the command `logout' to terminate, you must use `exit' or ^D.
When you terminate a sub-shell, you are returned to the process or shell that created it.

Example (starting from a bash shell)
$ tcsh
% # now in the tcsh shell
% exit
$ # now back in the bash shell
$ logout

"We want the finest wines available to humanity. And we want them here and we want them now" - Bruce Robinson / Withnail and I

Related:

exit - Exit session
- End of File
logname - Print current login name
Equivalent Windows command: EXIT - Quit the CMD shell

ln - Linux Man Page

SYNOPSIS
ln [OPTION]... [-T] TARGET LINK_NAME (1st form)
ln [OPTION]... TARGET (2nd form)
ln [OPTION]... TARGET... DIRECTORY (3rd form)
ln [OPTION]... -t DIRECTORY TARGET... (4th form)

DESCRIPTION
In the 1st form, create a link to TARGET with the name LINK_NAME. In
the 2nd form, create a link to TARGET in the current directory. In the
3rd and 4th forms, create links to each TARGET in DIRECTORY. Create
hard links by default, symbolic links with --symbolic. When creating
hard links, each TARGET must exist.

Mandatory arguments to long options are mandatory for short options
too.

--backup[=CONTROL]
make a backup of each existing destination file

-b like --backup but does not accept an argument

-d, -F, --directory
allow the superuser to attempt to hard link directories (note:
will probably fail due to system restrictions, even for the
superuser)

-f, --force
remove existing destination files

-n, --no-dereference
treat destination that is a symlink to a directory as if it were
a normal file

-i, --interactive
prompt whether to remove destinations

-s, --symbolic
make symbolic links instead of hard links

-S, --suffix=SUFFIX
override the usual backup suffix

-t, --target-directory=DIRECTORY
specify the DIRECTORY in which to create the links

-T, --no-target-directory
treat LINK_NAME as a normal file

-v, --verbose
print name of each linked file

--help display this help and exit

make numbered backups

existing, nil
numbered if numbered backups exist, simple otherwise

simple, never
always make simple backups

Basic Linux Commands





Command

Example

Description


cat


Sends file contents to standard output. This is a way to list the contents of short files to the screen. It works well with piping.


cat .bashrc

Sends the contents of the ".bashrc" file to the screen.

cd


Change directory


cd /home

Change the current working directory to /home. The '/' indicates relative to root, and no matter what directory you are in when you execute this command, the directory will be changed to "/home".


cd httpd

Change the current working directory to httpd, relative to the current location which is "/home". The full path of the new working directory is "/home/httpd".


cd ..

Move to the parent directory of the current directory. This command will make the current working directory "/home.


cd ~

Move to the user's home directory which is "/home/username". The '~' indicates the users home directory.

cp


Copy files


cp myfile yourfile

Copy the files "myfile" to the file "yourfile" in the current working directory. This command will create the file "yourfile" if it doesn't exist. It will normally overwrite it without warning if it exists.


cp -i myfile yourfile

With the "-i" option, if the file "yourfile" exists, you will be prompted before it is overwritten.


cp -i /data/myfile .

Copy the file "/data/myfile" to the current working directory and name it "myfile". Prompt before overwriting the file.


cp -dpr srcdir destdir

Copy all files from the directory "srcdir" to the directory "destdir" preserving links (-p option), file attributes (-p option), and copy recursively (-r option). With these options, a directory and all it contents can be copied to another directory.

dd

dd if=/dev/hdb1 of=/backup/

Disk duplicate. The man page says this command is to "Convert and copy a file", but although used by more advanced users, it can be a very handy command. The "if" means input file, "of" means output file.

df


Show the amount of disk space used on each mounted filesystem.

less

less textfile

Similar to the more command, but the user can page up and down through the file. The example displays the contents of textfile.

ln


Creates a symbolic link to a file.


ln -s test symlink

Creates a symbolic link named symlink that points to the file test Typing "ls -i test symlink" will show the two files are different with different inodes. Typing "ls -l test symlink" will show that symlink points to the file test.

locate


A fast database driven file locator.


slocate -u

This command builds the slocate database. It will take several minutes to complete this command. This command must be used before searching for files, however cron runs this command periodically on most systems.


locate whereis

Lists all files whose names contain the string "whereis".

logout


Logs the current user off the system.

ls


List files


ls

List files in the current working directory except those starting with . and only show the file name.


ls -al

List all files in the current working directory in long listing format showing permissions, ownership, size, and time and date stamp

more


Allows file contents or piped output to be sent to the screen one page at a time.


more /etc/profile

Lists the contents of the "/etc/profile" file to the screen one page at a time.


ls -al |more

Performs a directory listing of all files and pipes the output of the listing through more. If the directory listing is longer than a page, it will be listed one page at a time.

mv


Move or rename files


mv -i myfile yourfile

Move the file from "myfile" to "yourfile". This effectively changes the name of "myfile" to "yourfile".


mv -i /data/myfile .

Move the file from "myfile" from the directory "/data" to the current working directory.

pwd


Show the name of the current working directory


more /etc/profile

Lists the contents of the "/etc/profile" file to the screen one page at a time.

shutdown


Shuts the system down.


shutdown -h now

Shuts the system down to halt immediately.


shutdown -r now

Shuts the system down immediately and the system reboots.

whereis


Show where the binary, source and manual page files are for a command


whereis ls

Locates binaries and manual pages for the ls command.







Editors: emacs, vi, pico, jed, vim


whereis - Linux Man Page

SYNOPSIS
whereis [ -bmsu ] [ -BMS directory... -f ] filename ...

DESCRIPTION
whereis locates source/binary and manuals sections for specified files.
The supplied names are first stripped of leading pathname components
and any (single) trailing extension of the form .ext, for example, .c.
Prefixes of s. resulting from use of source code control are also
dealt with. whereis then attempts to locate the desired program in a
list of standard Linux places.

OPTIONS
-b Search only for binaries.

-m Search only for manual sections.

-s Search only for sources.

-u Search for unusual entries. A file is said to be unusual if it
does not have one entry of each requested type. Thus
`whereis -m -u *' asks for those files in the current direc-
tory which have no documentation.

-B Change or otherwise limit the places where whereis searches for
binaries.

-M Change or otherwise limit the places where whereis searches for
manual sections.

-S Change or otherwise limit the places where whereis searches for
sources.

-f Terminate the last directory list and signals the start of file
names, and must be used when any of the -B, -M, or -S options
are used.

EXAMPLE
Find all files in /usr/bin which are not documented in /usr/man/man1
with source in /usr/src:

example% cd /usr/bin
example% whereis -u -M /usr/man/man1 -S /usr/src -f *

FILES
/{bin,sbin,etc}

/usr/{lib,bin,old,new,local,games,include,etc,src,man,sbin,
X386,TeX,g++-include}

/usr/local/{X386,TeX,X11,include,lib,man,etc,bin,games,emacs}

pwd - Linux Man page

SYNOPSIS
pwd [OPTION]

DESCRIPTION
Print the full filename of the current working directory.

--help display this help and exit

--version
output version information and exit

NOTE: your shell may have its own version of pwd, which usually super-
sedes the version described here. Please refer to your shell's docu-
mentation for details about the options it supports.

COPYRIGHT
Copyright (C) 2008 Free Software Foundation, Inc. License GPLv3+: GNU
GPL version 3 or later
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.

mv - Linux Man Page

SYNOPSIS
mv [OPTION]... [-T] SOURCE DEST
mv [OPTION]... SOURCE... DIRECTORY
mv [OPTION]... -t DIRECTORY SOURCE...

DESCRIPTION
Rename SOURCE to DEST, or move SOURCE(s) to DIRECTORY.

Mandatory arguments to long options are mandatory for short options
too.

--backup[=CONTROL]
make a backup of each existing destination file

-b like --backup but does not accept an argument

-f, --force
do not prompt before overwriting

-i, --interactive
prompt before overwrite

--strip-trailing-slashes
remove any trailing slashes from each SOURCE argument

-S, --suffix=SUFFIX
override the usual backup suffix

-t, --target-directory=DIRECTORY
move all SOURCE arguments into DIRECTORY

-T, --no-target-directory
treat DEST as a normal file

-u, --update
move only when the SOURCE file is newer than the destination
file or when the destination file is missing

-v, --verbose
explain what is being done

--help display this help and exit

--version
output version information and exit

The backup suffix is `~', unless set with --suffix or SIM-
PLE_BACKUP_SUFFIX. The version control method may be selected via the
--backup option or through the VERSION_CONTROL environment variable.
Here are the values:

none, off
never make backups (even if --backup is given)

REPORTING BUGS
Report bugs to .

COPYRIGHT
Copyright (C) 2008 Free Software Foundation, Inc. License GPLv3+: GNU
GPL version 3 or later
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.

more -Linux Man Page

SYNOPSIS
more [-dlfpcsu] [-num] [+/ pattern] [+ linenum] [file ...]

DESCRIPTION
More is a filter for paging through text one screenful at a time. This
version is especially primitive. Users should realize that less(1) pro-
vides more(1) emulation and extensive enhancements.

OPTIONS
Command line options are described below. Options are also taken from
the environment variable MORE (make sure to precede them with a dash
(``-'')) but command line options will override them.

-num This option specifies an integer which is the screen size (in
lines).

-d more will prompt the user with the message "[Press space to con-
tinue, 'q' to quit.]" and will display "[Press 'h' for instruc-
tions.]" instead of ringing the bell when an illegal key is
pressed.

-l more usually treats ^L (form feed) as a special character, and will
pause after any line that contains a form feed. The -l option will
prevent this behavior.

-f Causes more to count logical, rather than screen lines (i.e., long
lines are not folded).

-p Do not scroll. Instead, clear the whole screen and then display
the text.

-c Do not scroll. Instead, paint each screen from the top, clearing
the remainder of each line as it is displayed.

-s Squeeze multiple blank lines into one.

-u Suppress underlining.

+/ The +/ option specifies a string that will be searched for before
each file is displayed.

+num Start at line number num.

COMMANDS
Interactive commands for more are based on vi(1). Some commands may be
preceded by a decimal number, called k in the descriptions below. In the
following descriptions, ^X means control-X.

h or ? Help: display a summary of these commands. If you forget all
the other commands, remember this one.

SPACE Display next k lines of text. Defaults to current screen
size.

z Display next k lines of text. Defaults to current screen

f Skip forward k screenfuls of text. Defaults to 1.

b or ^B Skip backwards k screenfuls of text. Defaults to 1. Only
works with files, not pipes.

' Go to place where previous search started.

= Display current line number.

/pattern Search for kth occurrence of regular expression. Defaults to
1.

n Search for kth occurrence of last r.e. Defaults to 1.

! or :!
Execute in a subshell

v Start up an editor at current line. The editor is taken from
the environment variable VISUAL if defined, or EDITOR if
VISUAL is not defined, or defaults to "vi" if neither VISUAL
nor EDITOR is defined.

^L Redraw screen

:n Go to kth next file. Defaults to 1.

:p Go to kth previous file. Defaults to 1.

:f Display current file name and line number

. Repeat previous command

ENVIRONMENT
More utilizes the following environment variables, if they exist:

MORE This variable may be set with favored options to more.

SHELL Current shell in use (normally set by the shell at login
time).

TERM Specifies terminal type, used by more to get the terminal
characteristics necessary to manipulate the screen.

ls -Linux Man Page

SYNOPSIS
ls [OPTION]... [FILE]...

DESCRIPTION
List information about the FILEs (the current directory by default).
Sort entries alphabetically if none of -cftuvSUX nor --sort.

Mandatory arguments to long options are mandatory for short options
too.

-a, --all
do not ignore entries starting with .

-A, --almost-all
do not list implied . and ..

--author
with -l, print the author of each file

-b, --escape
print octal escapes for nongraphic characters

--block-size=SIZE
use SIZE-byte blocks

-B, --ignore-backups
do not list implied entries ending with ~

-c with -lt: sort by, and show, ctime (time of last modification of
file status information) with -l: show ctime and sort by name
otherwise: sort by ctime

-C list entries by columns

--color[=WHEN]
control whether color is used to distinguish file types. WHEN
may be `never', `always', or `auto'

-d, --directory
list directory entries instead of contents, and do not derefer-
ence symbolic links

-D, --dired
generate output designed for Emacs' dired mode

-f do not sort, enable -aU, disable -ls --color

-F, --classify
append indicator (one of */=>@|) to entries

--file-type
likewise, except do not append `*'

-G, --no-group
in a long listing, don't print group names

-h, --human-readable
with -l, print sizes in human readable format (e.g., 1K 234M 2G)

--si likewise, but use powers of 1000 not 1024

-H, --dereference-command-line
follow symbolic links listed on the command line

--dereference-command-line-symlink-to-dir
follow each command line symbolic link that points to a direc-
tory

--hide=PATTERN
do not list implied entries matching shell PATTERN (overridden
by -a or -A)

--indicator-style=WORD
append indicator with style WORD to entry names: none (default),
slash (-p), file-type (--file-type), classify (-F)

-i, --inode
print the index number of each file

-I, --ignore=PATTERN
do not list implied entries matching shell PATTERN

-k like --block-size=1K

-l use a long listing format

-L, --dereference
when showing file information for a symbolic link, show informa-
tion for the file the link references rather than for the link
itself

-m fill width with a comma separated list of entries

-n, --numeric-uid-gid
like -l, but list numeric user and group IDs

-N, --literal
print raw entry names (don't treat e.g. control characters spe-
cially)

-o like -l, but do not list group information

-p, --indicator-style=slash
append / indicator to directories

-q, --hide-control-chars
print ? instead of non graphic characters

-r, --reverse
reverse order while sorting

-R, --recursive
list subdirectories recursively

-s, --size
print the size of each file, in blocks

-S sort by file size

--sort=WORD
sort by WORD instead of name: none -U, extension -X, size -S,
time -t, version -v

--time=WORD
with -l, show time as WORD instead of modification time: atime
-u, access -u, use -u, ctime -c, or status -c; use specified
time as sort key if --sort=time

--time-style=STYLE
with -l, show times using style STYLE: full-iso, long-iso, iso,
locale, +FORMAT. FORMAT is interpreted like `date'; if FORMAT
is FORMAT1FORMAT2, FORMAT1 applies to non-recent files
and FORMAT2 to recent files; if STYLE is prefixed with `posix-',
STYLE takes effect only outside the POSIX locale

-t sort by modification time

-T, --tabsize=COLS
assume tab stops at each COLS instead of 8

-u with -lt: sort by, and show, access time with -l: show access
time and sort by name otherwise: sort by access time

-U do not sort; list entries in directory order

-v sort by version

-w, --width=COLS
assume screen width instead of current value

-x list entries by lines instead of by columns

-X sort alphabetically by entry extension

-Z, --context
print any SELinux security context of each file

-1 list one file per line

--help display this help and exit

--version

Exit status is 0 if OK, 1 if minor problems, 2 if serious trouble.

COPYRIGHT
Copyright (C) 2008 Free Software Foundation, Inc. License GPLv3+: GNU
GPL version 3 or later
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.


locate - Linux Man Page



SYNOPSIS

locate [-d path | --database=path] [-e | --existing] [-i | --ignore-case ] [--version] [--help] pattern...
DESCRIPTION
This manual page documents the GNU version of locate. For each given pattern, locate searches one or more databases of file names and displays the file names that contain the pattern. Patterns can contain shell-style metacharacters: `*', `?', and `[]'. The metacharacters do not treat `/' or `.' specially. Therefore, a pattern `foo*bar' can match a file name that contains `foo3/bar', and a pattern `*duck*' can match a file name that contains `lake/.ducky'. Patterns that contain metacharacters should be quoted to protect them from expansion by the shell. If a pattern is a plain string --- it contains no metacharacters --- locate displays all file names in the database that contain that string anywhere. If a pattern does contain metacharacters, locate only displays file names that match the pattern exactly. As a result, patterns that contain metacharacters should usually begin with a `*', and will most often end with one as well. The exceptions are patterns that are intended to explicitly match the beginning or end of a file name. The file name databases contain lists of files that were on the system when the databases were last updated. The system administrator can choose the file name of the default database, the frequency with which the databases are updated, and the directories for which they contain entries; see updatedb(1L).
OPTIONS

-d path, --database=path
Instead of searching the default file name database, search the file name databases in path, which is a colon-separated list of database file names. You can also use the environment variable LOCATE_PATH to set the list of database files to search. The option overrides the environment variable if both are used. The file name database format changed starting with GNU find and locate version 4.0 to allow machines with diffent byte orderings to share the databases. This version of locate can automatically recognize and read databases produced for older versions of GNU locate or Unix versions of locate or find.
-e, --existing
Only print out such names that currently exist (instead of such names that existed when the database was created). Note that this may slow down the program a lot, if there are many matches in the database.
-i, --ignore-case
Ignore case distinctions in both the pattern and the file names.
--help
Print a summary of the options to locate and exit.
--version
Print the version number of locate and exit.


ENVIRONMENT

LOCATE_PATH
Colon-separated list of databases to search.

Tuesday, April 21, 2009

less - Linux Man Page

SYNOPSIS
less -?
less --help
less -V
less --version
less [-[+]aBcCdeEfFgGiIJKLmMnNqQrRsSuUVwWX~]
[-b space] [-h lines] [-j line] [-k keyfile]
[-{oO} logfile] [-p pattern] [-P prompt] [-t tag]
[-T tagsfile] [-x tab,...] [-y lines] [-[z] lines]
[-# shift] [+[+]cmd] [--] [filename]...
(See the OPTIONS section for alternate option syntax with long option
names.)


DESCRIPTION
Less is a program similar to more (1), but which allows backward move-
ment in the file as well as forward movement. Also, less does not have
to read the entire input file before starting, so with large input
files it starts up faster than text editors like vi (1). Less uses
termcap (or terminfo on some systems), so it can run on a variety of
terminals. There is even limited support for hardcopy terminals. (On
a hardcopy terminal, lines which should be printed at the top of the
screen are prefixed with a caret.)

Commands are based on both more and vi. Commands may be preceded by a
decimal number, called N in the descriptions below. The number is used
by some commands, as indicated.


COMMANDS
In the following descriptions, ^X means control-X. ESC stands for the
ESCAPE key; for example ESC-v means the two character sequence
"ESCAPE", then "v".

h or H Help: display a summary of these commands. If you forget all
the other commands, remember this one.

SPACE or ^V or f or ^F
Scroll forward N lines, default one window (see option -z
below). If N is more than the screen size, only the final
screenful is displayed. Warning: some systems use ^V as a spe-
cial literalization character.

z Like SPACE, but if N is specified, it becomes the new window
size.

ESC-SPACE
Like SPACE, but scrolls a full screenful, even if it reaches
end-of-file in the process.

RETURN or ^N or e or ^E or j or ^J
Scroll forward N lines, default 1. The entire N lines are dis-
played, even if N is more than the screen size.
size.

y or ^Y or ^P or k or ^K
Scroll backward N lines, default 1. The entire N lines are dis-
played, even if N is more than the screen size. Warning: some
systems use ^Y as a special job control character.

u or ^U
Scroll backward N lines, default one half of the screen size.
If N is specified, it becomes the new default for subsequent d
and u commands.

ESC-) or RIGHTARROW
Scroll horizontally right N characters, default half the screen
width (see the -# option). If a number N is specified, it
becomes the default for future RIGHTARROW and LEFTARROW com-
mands. While the text is scrolled, it acts as though the -S
option (chop lines) were in effect.

ESC-( or LEFTARROW
Scroll horizontally left N characters, default half the screen
width (see the -# option). If a number N is specified, it
becomes the default for future RIGHTARROW and LEFTARROW com-
mands.

r or ^R or ^L
Repaint the screen.

R Repaint the screen, discarding any buffered input. Useful if
the file is changing while it is being viewed.

F Scroll forward, and keep trying to read when the end of file is
reached. Normally this command would be used when already at
the end of the file. It is a way to monitor the tail of a file
which is growing while it is being viewed. (The behavior is
similar to the "tail -f" command.)

g or < or ESC-<
Go to line N in the file, default 1 (beginning of file). (Warn-
ing: this may be slow if N is large.)

G or > or ESC->
Go to line N in the file, default the end of the file. (Warn-
ing: this may be slow if N is large, or if N is not specified
and standard input, rather than a file, is being read.)

p or % Go to a position N percent into the file. N should be between 0
and 100, and may contain a decimal point.

P Go to the line containing byte offset N in the file.

{ If a left curly bracket appears in the top line displayed on the
screen, the { command will go to the matching right curly
bracket. The matching right curly bracket is positioned on the

) Like }, but applies to parentheses rather than curly brackets.

[ Like {, but applies to square brackets rather than curly brack-
ets.

] Like }, but applies to square brackets rather than curly brack-
ets.

ESC-^F Followed by two characters, acts like {, but uses the two char-
acters as open and close brackets, respectively. For example,
"ESC ^F < >" could be used to go forward to the > which matches
the < in the top displayed line.

ESC-^B Followed by two characters, acts like }, but uses the two char-
acters as open and close brackets, respectively. For example,
"ESC ^B < >" could be used to go backward to the < which matches
the > in the bottom displayed line.

m Followed by any lowercase letter, marks the current position
with that letter.

' (Single quote.) Followed by any lowercase letter, returns to
the position which was previously marked with that letter. Fol-
lowed by another single quote, returns to the position at which
the last "large" movement command was executed. Followed by a ^
or $, jumps to the beginning or end of the file respectively.
Marks are preserved when a new file is examined, so the ' com-
mand can be used to switch between input files.

^X^X Same as single quote.

/pattern
Search forward in the file for the N-th line containing the pat-
tern. N defaults to 1. The pattern is a regular expression, as
recognized by the regular expression library supplied by your
system. The search starts at the second line displayed (but see
the -a and -j options, which change this).

Certain characters are special if entered at the beginning of
the pattern; they modify the type of search rather than become
part of the pattern:

^N or !
Search for lines which do NOT match the pattern.

^E or *
Search multiple files. That is, if the search reaches
the END of the current file without finding a match, the
search continues in the next file in the command line
list.

^F or @
Begin the search at the first line of the FIRST file in

Search backward in the file for the N-th line containing the
pattern. The search starts at the line immediately before the
top line displayed.

Certain characters are special as in the / command:

^N or !
Search for lines which do NOT match the pattern.

^E or *
Search multiple files. That is, if the search reaches
the beginning of the current file without finding a
match, the search continues in the previous file in the
command line list.

^F or @
Begin the search at the last line of the last file in the
command line list, regardless of what is currently dis-
played on the screen or the settings of the -a or -j
options.

^K As in forward searches.

^R As in forward searches.

ESC-/pattern
Same as "/*".

ESC-?pattern
Same as "?*".

n Repeat previous search, for N-th line containing the last pat-
tern. If the previous search was modified by ^N, the search is
made for the N-th line NOT containing the pattern. If the pre-
vious search was modified by ^E, the search continues in the
next (or previous) file if not satisfied in the current file.
If the previous search was modified by ^R, the search is done
without using regular expressions. There is no effect if the
previous search was modified by ^F or ^K.

N Repeat previous search, but in the reverse direction.

ESC-n Repeat previous search, but crossing file boundaries. The
effect is as if the previous search were modified by *.

ESC-N Repeat previous search, but in the reverse direction and cross-
ing file boundaries.

ESC-u Undo search highlighting. Turn off highlighting of strings
matching the current search pattern. If highlighting is already
off because of a previous ESC-u command, turn highlighting back
on. Any search command will also turn highlighting back on.
(Highlighting can also be disabled by toggling the -G option; in
that case search commands do not turn highlighting back on.)
files so that it can be seen by subsequent :n and :p commands.
If the filename consists of several files, they are all inserted
into the list of files and the first one is examined. If the
filename contains one or more spaces, the entire filename should
be enclosed in double quotes (also see the -" option).

^X^V or E
Same as :e. Warning: some systems use ^V as a special literal-
ization character. On such systems, you may not be able to use
^V.

:n Examine the next file (from the list of files given in the com-
mand line). If a number N is specified, the N-th next file is
examined.

:p Examine the previous file in the command line list. If a number
N is specified, the N-th previous file is examined.

:x Examine the first file in the command line list. If a number N
is specified, the N-th file in the list is examined.

:d Remove the current file from the list of files.

t Go to the next tag, if there were more than one matches for the
current tag. See the -t option for more details about tags.

T Go to the previous tag, if there were more than one matches for
the current tag.

= or ^G or :f
Prints some information about the file being viewed, including
its name and the line number and byte offset of the bottom line
being displayed. If possible, it also prints the length of the
file, the number of lines in the file and the percent of the
file above the last displayed line.

- Followed by one of the command line option letters (see OPTIONS
below), this will change the setting of that option and print a
message describing the new setting. If a ^P (CONTROL-P) is
entered immediately after the dash, the setting of the option is
changed but no message is printed. If the option letter has a
numeric value (such as -b or -h), or a string value (such as -P
or -t), a new value may be entered after the option letter. If
no new value is entered, a message describing the current set-
ting is printed and nothing is changed.

-- Like the - command, but takes a long option name (see OPTIONS
below) rather than a single option letter. You must press
RETURN after typing the option name. A ^P immediately after the
second dash suppresses printing of a message describing the new
setting, as in the - command.

-+ Followed by one of the command line option letters this will
reset the option to its default setting and print a message

--! Like the -! command, but takes a long option name rather than a
single option letter.

_ (Underscore.) Followed by one of the command line option let-
ters, this will print a message describing the current setting
of that option. The setting of the option is not changed.

__ (Double underscore.) Like the _ (underscore) command, but takes
a long option name rather than a single option letter. You must
press RETURN after typing the option name.

+cmd Causes the specified cmd to be executed each time a new file is
examined. For example, +G causes less to initially display each
file starting at the end rather than the beginning.

V Prints the version number of less being run.

q or Q or :q or :Q or ZZ
Exits less.

The following four commands may or may not be valid, depending on your
particular installation.


v Invokes an editor to edit the current file being viewed. The
editor is taken from the environment variable VISUAL if defined,
or EDITOR if VISUAL is not defined, or defaults to "vi" if nei-
ther VISUAL nor EDITOR is defined. See also the discussion of
LESSEDIT under the section on PROMPTS below.

! shell-command
Invokes a shell to run the shell-command given. A percent sign
(%) in the command is replaced by the name of the current file.
A pound sign (#) is replaced by the name of the previously exam-
ined file. "!!" repeats the last shell command. "!" with no
shell command simply invokes a shell. On Unix systems, the
shell is taken from the environment variable SHELL, or defaults
to "sh". On MS-DOS and OS/2 systems, the shell is the normal
command processor.

| shell-command
represents any mark letter. Pipes a section of the input
file to the given shell command. The section of the file to be
piped is between the first line on the current screen and the
position marked by the letter. may also be ^ or $ to indi-
cate beginning or end of file respectively. If is . or new-
line, the current screen is piped.

s filename
Save the input to a file. This only works if the input is a
pipe, not an ordinary file.


OPTIONS

Options are also taken from the environment variable "LESS". For exam-
ple, to avoid typing "less -options ..." each time less is invoked, you
might tell csh:

setenv LESS "-options"

or if you use sh:

LESS="-options"; export LESS

On MS-DOS, you don't need the quotes, but you should replace any per-
cent signs in the options string by double percent signs.

The environment variable is parsed before the command line, so command
line options override the LESS environment variable. If an option
appears in the LESS variable, it can be reset to its default value on
the command line by beginning the command line option with "-+".

For options like -P or -D which take a following string, a dollar sign
($) must be used to signal the end of the string. For example, to set
two -D options on MS-DOS, you must have a dollar sign between them,
like this:

LESS="-Dn9.1$-Ds4.1"


-? or --help
This option displays a summary of the commands accepted by less
(the same as the h command). (Depending on how your shell
interprets the question mark, it may be necessary to quote the
question mark, thus: "-\?".)

-a or --search-skip-screen
Causes searches to start after the last line displayed on the
screen, thus skipping all lines displayed on the screen. By
default, searches start at the second line on the screen (or
after the last found line; see the -j option).

-bn or --buffers=n
Specifies the amount of buffer space less will use for each
file, in units of kilobytes (1024 bytes). By default 64K of
buffer space is used for each file (unless the file is a pipe;
see the -B option). The -b option specifies instead that n
kilobytes of buffer space should be used for each file. If n is
-1, buffer space is unlimited; that is, the entire file can be
read into memory.

-B or --auto-buffers
By default, when data is read from a pipe, buffers are allocated
automatically as needed. If a large amount of data is read from
the pipe, this can cause a large amount of memory to be allo-
cated. The -B option disables this automatic allocation of
buffers for pipes, so that only 64K (or the amount of space

-d or --dumb
The -d option suppresses the error message normally displayed if
the terminal is dumb; that is, lacks some important capability,
such as the ability to clear the screen or scroll backward. The
-d option does not otherwise change the behavior of less on a
dumb terminal.

-Dxcolor or --color=xcolor
[MS-DOS only] Sets the color of the text displayed. x is a sin-
gle character which selects the type of text whose color is
being set: n=normal, s=standout, d=bold, u=underlined, k=blink.
color is a pair of numbers separated by a period. The first
number selects the foreground color and the second selects the
background color of the text. A single number N is the same as
N.0.

-e or --quit-at-eof
Causes less to automatically exit the second time it reaches
end-of-file. By default, the only way to exit less is via the
"q" command.

-E or --QUIT-AT-EOF
Causes less to automatically exit the first time it reaches end-
of-file.

-f or --force
Forces non-regular files to be opened. (A non-regular file is a
directory or a device special file.) Also suppresses the warn-
ing message when a binary file is opened. By default, less will
refuse to open non-regular files. Note that some operating sys-
tems will not allow directories to be read, even if -f is set.

-F or --quit-if-one-screen
Causes less to automatically exit if the entire file can be dis-
played on the first screen.

-g or --hilite-search
Normally, less will highlight ALL strings which match the last
search command. The -g option changes this behavior to high-
light only the particular string which was found by the last
search command. This can cause less to run somewhat faster than
the default.

-G or --HILITE-SEARCH
The -G option suppresses all highlighting of strings found by
search commands.

-hn or --max-back-scroll=n
Specifies a maximum number of lines to scroll backward. If it
is necessary to scroll backward more than n lines, the screen is
repainted in a forward direction instead. (If the terminal does
not have the ability to scroll backward, -h0 is implied.)

Specifies a line on the screen where the "target" line is to be
positioned. The target line is the line specified by any com-
mand to search for a pattern, jump to a line number, jump to a
file percentage or jump to a tag. The screen line may be speci-
fied by a number: the top line on the screen is 1, the next is
2, and so on. The number may be negative to specify a line rel-
ative to the bottom of the screen: the bottom line on the screen
is -1, the second to the bottom is -2, and so on. Alternately,
the screen line may be specified as a fraction of the height of
the screen, starting with a decimal point: .5 is in the middle
of the screen, .3 is three tenths down from the first line, and
so on. If the line is specified as a fraction, the actual line
number is recalculated if the terminal window is resized, so
that the target line remains at the specified fraction of the
screen height. If any form of the -j option is used, forward
searches begin at the line immediately after the target line,
and backward searches begin at the target line. For example, if
"-j4" is used, the target line is the fourth line on the screen,
so forward searches begin at the fifth line on the screen.

-J or --status-column
Displays a status column at the left edge of the screen. The
status column shows the lines that matched the current search.
The status column is also used if the -w or -W option is in
effect.

-kfilename or --lesskey-file=filename
Causes less to open and interpret the named file as a lesskey
(1) file. Multiple -k options may be specified. If the LESSKEY
or LESSKEY_SYSTEM environment variable is set, or if a lesskey
file is found in a standard place (see KEY BINDINGS), it is also
used as a lesskey file.

-K or --quit-on-intr
Causes less to exit immediately when an interrupt character
(usually ^C) is typed. Normally, an interrupt character causes
less to stop whatever it is doing and return to its command
prompt. Note that use of this option makes it impossible to
return to the command prompt from the "F" command.

-L or --no-lessopen
Ignore the LESSOPEN environment variable (see the INPUT PREPRO-
CESSOR section below). This option can be set from within less,
but it will apply only to files opened subsequently, not to the
file which is currently open.

-m or --long-prompt
Causes less to prompt verbosely (like more), with the percent
into the file. By default, less prompts with a colon.

-M or --LONG-PROMPT
Causes less to prompt even more verbosely than more.

-n or --line-numbers

-ofilename or --log-file=filename
Causes less to copy its input to the named file as it is being
viewed. This applies only when the input file is a pipe, not an
ordinary file. If the file already exists, less will ask for
confirmation before overwriting it.

-Ofilename or --LOG-FILE=filename
The -O option is like -o, but it will overwrite an existing file
without asking for confirmation.

If no log file has been specified, the -o and -O options can be
used from within less to specify a log file. Without a file
name, they will simply report the name of the log file. The "s"
command is equivalent to specifying -o from within less.

-ppattern or --pattern=pattern
The -p option on the command line is equivalent to specifying
+/pattern; that is, it tells less to start at the first occur-
rence of pattern in the file.

-Pprompt or --prompt=prompt
Provides a way to tailor the three prompt styles to your own
preference. This option would normally be put in the LESS envi-
ronment variable, rather than being typed in with each less com-
mand. Such an option must either be the last option in the LESS
variable, or be terminated by a dollar sign. -Ps followed by a
string changes the default (short) prompt to that string. -Pm
changes the medium (-m) prompt. -PM changes the long (-M)
prompt. -Ph changes the prompt for the help screen. -P=
changes the message printed by the = command. -Pw changes the
message printed while waiting for data (in the F command). All
prompt strings consist of a sequence of letters and special
escape sequences. See the section on PROMPTS for more details.

-q or --quiet or --silent
Causes moderately "quiet" operation: the terminal bell is not
rung if an attempt is made to scroll past the end of the file or
before the beginning of the file. If the terminal has a "visual
bell", it is used instead. The bell will be rung on certain
other errors, such as typing an invalid character. The default
is to ring the terminal bell in all such cases.

-Q or --QUIET or --SILENT
Causes totally "quiet" operation: the terminal bell is never
rung.

-r or --raw-control-chars
Causes "raw" control characters to be displayed. The default is
to display control characters using the caret notation; for
example, a control-A (octal 001) is displayed as "^A". Warning:
when the -r option is used, less cannot keep track of the actual
appearance of the screen (since this depends on how the screen
responds to each type of control character). Thus, various dis-
For the purpose of keeping track of screen appearance, ANSI
color escape sequences are assumed to not move the cursor. You
can make less think that characters other than "m" can end ANSI
color escape sequences by setting the environment variable
LESSANSIENDCHARS to the list of characters which can end a color
escape sequence. And you can make less think that characters
other than the standard ones may appear between the ESC and the
m by setting the environment variable LESSANSIMIDCHARS to the
list of characters which can appear.

-s or --squeeze-blank-lines
Causes consecutive blank lines to be squeezed into a single
blank line. This is useful when viewing nroff output.

-S or --chop-long-lines
Causes lines longer than the screen width to be chopped rather
than folded. That is, the portion of a long line that does not
fit in the screen width is not shown. The default is to fold
long lines; that is, display the remainder on the next line.

-ttag or --tag=tag
The -t option, followed immediately by a TAG, will edit the file
containing that tag. For this to work, tag information must be
available; for example, there may be a file in the current
directory called "tags", which was previously built by ctags (1)
or an equivalent command. If the environment variable LESSGLOB-
ALTAGS is set, it is taken to be the name of a command compati-
ble with global (1), and that command is executed to find the
tag. (See http://www.gnu.org/software/global/global.html). The
-t option may also be specified from within less (using the -
command) as a way of examining a new file. The command ":t" is
equivalent to specifying -t from within less.

-Ttagsfile or --tag-file=tagsfile
Specifies a tags file to be used instead of "tags".

-u or --underline-special
Causes backspaces and carriage returns to be treated as print-
able characters; that is, they are sent to the terminal when
they appear in the input.

-U or --UNDERLINE-SPECIAL
Causes backspaces, tabs and carriage returns to be treated as
control characters; that is, they are handled as specified by
the -r option.

By default, if neither -u nor -U is given, backspaces which
appear adjacent to an underscore character are treated spe-
cially: the underlined text is displayed using the terminal's
hardware underlining capability. Also, backspaces which appear
between two identical characters are treated specially: the
overstruck text is printed using the terminal's hardware bold-
face capability. Other backspaces are deleted, along with the
preceding character. Carriage returns immediately followed by a
The highlight is removed at the next command which causes move-
ment. The entire line is highlighted, unless the -J option is
in effect, in which case only the status column is highlighted.

-W or --HILITE-UNREAD
Like -w, but temporarily highlights the first new line after any
forward movement command larger than one line.

-xn,... or --tabs=n,...
Sets tab stops. If only one n is specified, tab stops are set
at multiples of n. If multiple values separated by commas are
specified, tab stops are set at those positions, and then con-
tinue with the same spacing as the last two. For example,
-x9,17 will set tabs at positions 9, 17, 25, 33, etc. The
default for n is 8.

-X or --no-init
Disables sending the termcap initialization and deinitialization
strings to the terminal. This is sometimes desirable if the
deinitialization string does something unnecessary, like clear-
ing the screen.

-yn or --max-forw-scroll=n
Specifies a maximum number of lines to scroll forward. If it is
necessary to scroll forward more than n lines, the screen is
repainted instead. The -c or -C option may be used to repaint
from the top of the screen if desired. By default, any forward
movement causes scrolling.

-[z]n or --window=n
Changes the default scrolling window size to n lines. The
default is one screenful. The z and w commands can also be used
to change the window size. The "z" may be omitted for compati-
bility with some versions of more. If the number n is negative,
it indicates n lines less than the current screen size. For
example, if the screen is 24 lines, -z-4 sets the scrolling win-
dow to 20 lines. If the screen is resized to 40 lines, the
scrolling window automatically changes to 36 lines.

-"cc or --quotes=cc
Changes the filename quoting character. This may be necessary
if you are trying to name a file which contains both spaces and
quote characters. Followed by a single character, this changes
the quote character to that character. Filenames containing a
space should then be surrounded by that character rather than by
double quotes. Followed by two characters, changes the open
quote to the first character, and the close quote to the second
character. Filenames containing a space should then be preceded
by the open quote character and followed by the close quote
character. Note that even after the quote characters are
changed, this option remains -" (a dash followed by a double
quote).

-~ or --tilde
strings to the terminal. This is sometimes useful if the keypad
strings make the numeric keypad behave in an undesirable manner.

--follow-name
Normally, if the input file is renamed while an F command is
executing, less will continue to display the contents of the
original file despite its name change. If --follow-name is
specified, during an F command less will periodically attempt to
reopen the file by name. If the reopen succeeds and the file is
a different file from the original (which means that a new file
has been created with the same name as the original (now
renamed) file), less will display the contents of that new file.

-- A command line argument of "--" marks the end of option argu-
ments. Any arguments following this are interpreted as file-
names. This can be useful when viewing a file whose name begins
with a "-" or "+".

+ If a command line option begins with +, the remainder of that
option is taken to be an initial command to less. For example,
+G tells less to start at the end of the file rather than the
beginning, and +/xyz tells it to start at the first occurrence
of "xyz" in the file. As a special case, + acts like
+g; that is, it starts the display at the specified line
number (however, see the caveat under the "g" command above).
If the option starts with ++, the initial command applies to
every file being viewed, not just the first one. The + command
described previously may also be used to set (or change) an ini-
tial command for every file.


LINE EDITING
When entering command line at the bottom of the screen (for example, a
filename for the :e command, or the pattern for a search command), cer-
tain keys can be used to manipulate the command line. Most commands
have an alternate form in [ brackets ] which can be used if a key does
not exist on a particular keyboard. (Note that the forms beginning
with ESC do not work in some MS-DOS and Windows systems because ESC is
the line erase character.) Any of these special keys may be entered
literally by preceding it with the "literal" character, either ^V or
^A. A backslash itself may also be entered literally by entering two
backslashes.

LEFTARROW [ ESC-h ]
Move the cursor one space to the left.

RIGHTARROW [ ESC-l ]
Move the cursor one space to the right.

^LEFTARROW [ ESC-b or ESC-LEFTARROW ]
(That is, CONTROL and LEFTARROW simultaneously.) Move the cur-
sor one word to the left.

^RIGHTARROW [ ESC-w or ESC-RIGHTARROW ]

DELETE or [ ESC-x ]
Delete the character under the cursor.

^BACKSPACE [ ESC-BACKSPACE ]
(That is, CONTROL and BACKSPACE simultaneously.) Delete the
word to the left of the cursor.

^DELETE [ ESC-X or ESC-DELETE ]
(That is, CONTROL and DELETE simultaneously.) Delete the word
under the cursor.

UPARROW [ ESC-k ]
Retrieve the previous command line.

DOWNARROW [ ESC-j ]
Retrieve the next command line.

TAB Complete the partial filename to the left of the cursor. If it
matches more than one filename, the first match is entered into
the command line. Repeated TABs will cycle thru the other
matching filenames. If the completed filename is a directory, a
"/" is appended to the filename. (On MS-DOS systems, a "\" is
appended.) The environment variable LESSSEPARATOR can be used
to specify a different character to append to a directory name.

BACKTAB [ ESC-TAB ]
Like, TAB, but cycles in the reverse direction thru the matching
filenames.

^L Complete the partial filename to the left of the cursor. If it
matches more than one filename, all matches are entered into the
command line (if they fit).

^U (Unix and OS/2) or ESC (MS-DOS)
Delete the entire command line, or cancel the command if the
command line is empty. If you have changed your line-kill char-
acter in Unix to something other than ^U, that character is used
instead of ^U.


KEY BINDINGS
You may define your own less commands by using the program lesskey (1)
to create a lesskey file. This file specifies a set of command keys
and an action associated with each key. You may also use lesskey to
change the line-editing keys (see LINE EDITING), and to set environment
variables. If the environment variable LESSKEY is set, less uses that
as the name of the lesskey file. Otherwise, less looks in a standard
place for the lesskey file: On Unix systems, less looks for a lesskey
file called "$HOME/.less". On MS-DOS and Windows systems, less looks
for a lesskey file called "$HOME/_less", and if it is not found there,
then looks for a lesskey file called "_less" in any directory specified
in the PATH environment variable. On OS/2 systems, less looks for a
lesskey file called "$HOME/less.ini", and if it is not found, then
Unix systems, the system-wide lesskey file is /usr/local/etc/sysless.
(However, if less was built with a different sysconf directory than
/usr/local/etc, that directory is where the sysless file is found.) On
MS-DOS and Windows systems, the system-wide lesskey file is c:\_sys-
less. On OS/2 systems, the system-wide lesskey file is c:\sysless.ini.


INPUT PREPROCESSOR
You may define an "input preprocessor" for less. Before less opens a
file, it first gives your input preprocessor a chance to modify the way
the contents of the file are displayed. An input preprocessor is sim-
ply an executable program (or shell script), which writes the contents
of the file to a different file, called the replacement file. The con-
tents of the replacement file are then displayed in place of the con-
tents of the original file. However, it will appear to the user as if
the original file is opened; that is, less will display the original
filename as the name of the current file.

An input preprocessor receives one command line argument, the original
filename, as entered by the user. It should create the replacement
file, and when finished, print the name of the replacement file to its
standard output. If the input preprocessor does not output a replace-
ment filename, less uses the original file, as normal. The input pre-
processor is not called when viewing standard input. To set up an
input preprocessor, set the LESSOPEN environment variable to a command
line which will invoke your input preprocessor. This command line
should include one occurrence of the string "%s", which will be
replaced by the filename when the input preprocessor command is
invoked.

When less closes a file opened in such a way, it will call another pro-
gram, called the input postprocessor, which may perform any desired
clean-up action (such as deleting the replacement file created by
LESSOPEN). This program receives two command line arguments, the orig-
inal filename as entered by the user, and the name of the replacement
file. To set up an input postprocessor, set the LESSCLOSE environment
variable to a command line which will invoke your input postprocessor.
It may include two occurrences of the string "%s"; the first is
replaced with the original name of the file and the second with the
name of the replacement file, which was output by LESSOPEN.

For example, on many Unix systems, these two scripts will allow you to
keep files in compressed format, but still let less view them directly:

lessopen.sh:
#! /bin/sh
case "$1" in
*.Z) uncompress -
if [ -s /tmp/less.$$ ]; then
echo /tmp/less.$$
else
rm -f /tmp/less.$$
fi
;;

data directly to less, rather than putting the data into a replacement
file. This avoids the need to decompress the entire file before start-
ing to view it. An input preprocessor that works this way is called an
input pipe. An input pipe, instead of writing the name of a replace-
ment file on its standard output, writes the entire contents of the
replacement file on its standard output. If the input pipe does not
write any characters on its standard output, then there is no replace-
ment file and less uses the original file, as normal. To use an input
pipe, make the first character in the LESSOPEN environment variable a
vertical bar (|) to signify that the input preprocessor is an input
pipe.

For example, on many Unix systems, this script will work like the pre-
vious example scripts:

lesspipe.sh:
#! /bin/sh
case "$1" in
*.Z) uncompress -c $1 2>/dev/null
;;
esac

To use this script, put it where it can be executed and set
LESSOPEN="|lesspipe.sh %s". When an input pipe is used, a LESSCLOSE
postprocessor can be used, but it is usually not necessary since there
is no replacement file to clean up. In this case, the replacement file
name passed to the LESSCLOSE postprocessor is "-".


NATIONAL CHARACTER SETS
There are three types of characters in the input file:

normal characters
can be displayed directly to the screen.

control characters
should not be displayed directly, but are expected to be found
in ordinary text files (such as backspace and tab).

binary characters
should not be displayed directly and are not expected to be
found in text files.

A "character set" is simply a description of which characters are to be
considered normal, control, and binary. The LESSCHARSET environment
variable may be used to select a character set. Possible values for
LESSCHARSET are:

ascii BS, TAB, NL, CR, and formfeed are control characters, all chars
with values between 32 and 126 are normal, and all others are
binary.

iso8859
Selects an ISO 8859 character set. This is the same as ASCII,
Selects an EBCDIC character set used by OS/390 Unix Services.
This is the EBCDIC analogue of latin1. You get similar results
by setting either LESSCHARSET=IBM-1047 or LC_CTYPE=en_US in your
environment.

koi8-r Selects a Russian character set.

next Selects a character set appropriate for NeXT computers.

utf-8 Selects the UTF-8 encoding of the ISO 10646 character set.
UTF-8 is special in that it supports multi-byte characters in
the input file. It is the only character set that supports
multi-byte characters.

windows
Selects a character set appropriate for Microsoft Windows (cp
1251).

In rare cases, it may be desired to tailor less to use a character set
other than the ones definable by LESSCHARSET. In this case, the envi-
ronment variable LESSCHARDEF can be used to define a character set. It
should be set to a string where each character in the string represents
one character in the character set. The character "." is used for a
normal character, "c" for control, and "b" for binary. A decimal num-
ber may be used for repetition. For example, "bccc4b." would mean
character 0 is binary, 1, 2 and 3 are control, 4, 5, 6 and 7 are
binary, and 8 is normal. All characters after the last are taken to be
the same as the last, so characters 9 through 255 would be normal.
(This is an example, and does not necessarily represent any real char-
acter set.)

This table shows the value of LESSCHARDEF which is equivalent to each
of the possible values for LESSCHARSET:

ascii 8bcccbcc18b95.b
dos 8bcccbcc12bc5b95.b.
ebcdic 5bc6bcc7bcc41b.9b7.9b5.b..8b6.10b6.b9.7b
9.8b8.17b3.3b9.7b9.8b8.6b10.b.b.b.
IBM-1047 4cbcbc3b9cbccbccbb4c6bcc5b3cbbc4bc4bccbc
191.b
iso8859 8bcccbcc18b95.33b.
koi8-r 8bcccbcc18b95.b128.
latin1 8bcccbcc18b95.33b.
next 8bcccbcc18b95.bb125.bb

If neither LESSCHARSET nor LESSCHARDEF is set, but any of the strings
"UTF-8", "UTF8", "utf-8" or "utf8" is found in the LC_ALL, LC_TYPE or
LANG environment variables, then the default character set is utf-8.

If that string is not found, but your system supports the setlocale
interface, less will use setlocale to determine the character set.
setlocale is controlled by setting the LANG or LC_CTYPE environment
variables.

attribute is assumed. The remainder of LESSBINFMT is a string which
may include one printf-style escape sequence (a % followed by x, X, o,
d, etc.). For example, if LESSBINFMT is "*u[%x]", binary characters
are displayed in underlined hexadecimal surrounded by brackets. The
default if no LESSBINFMT is specified is "*s<%X>". The default if no
LESSBINFMT is specified is "*s<%02X>". Warning: the result of expand-
ing the character via LESSBINFMT must be less than 31 characters.

When the character set is utf-8, the LESSUTFBINFMT environment variable
acts similarly to LESSBINFMT but it applies to Unicode code points that
were successfully decoded but are unsuitable for display (e.g., unas-
signed code points). Its default value is "". Note that
LESSUTFBINFMT and LESSBINFMT share their display attribute setting
("*x") so specifying one will affect both; LESSUTFBINFMT is read after
LESSBINFMT so its setting, if any, will have priority. Problematic
octets in a UTF-8 file (octets of a truncated sequence, octets of a
complete but non-shortest form sequence, illegal octets, and stray
trailing octets) are displayed individually using LESSBINFMT so as to
facilitate diagnostic of how the UTF-8 file is ill-formed.


PROMPTS
The -P option allows you to tailor the prompt to your preference. The
string given to the -P option replaces the specified prompt string.
Certain characters in the string are interpreted specially. The prompt
mechanism is rather complicated to provide flexibility, but the ordi-
nary user need not understand the details of constructing personalized
prompt strings.

A percent sign followed by a single character is expanded according to
what the following character is:

%bX Replaced by the byte offset into the current input file. The b
is followed by a single character (shown as X above) which spec-
ifies the line whose byte offset is to be used. If the charac-
ter is a "t", the byte offset of the top line in the display is
used, an "m" means use the middle line, a "b" means use the bot-
tom line, a "B" means use the line just after the bottom line,
and a "j" means use the "target" line, as specified by the -j
option.

%B Replaced by the size of the current input file.

%c Replaced by the column number of the text appearing in the first
column of the screen.

%dX Replaced by the page number of a line in the input file. The
line to be used is determined by the X, as with the %b option.

%D Replaced by the number of pages in the input file, or equiva-
lently, the page number of the last line in the input file.

%E Replaced by the name of the editor (from the VISUAL environment
variable, or the EDITOR environment variable if VISUAL is not

%m Replaced by the total number of input files.

%pX Replaced by the percent into the current input file, based on
byte offsets. The line used is determined by the X as with the
%b option.

%PX Replaced by the percent into the current input file, based on
line numbers. The line used is determined by the X as with the
%b option.

%s Same as %B.

%t Causes any trailing spaces to be removed. Usually used at the
end of the string, but may appear anywhere.

%x Replaced by the name of the next input file in the list.

If any item is unknown (for example, the file size if input is a pipe),
a question mark is printed instead.

The format of the prompt string can be changed depending on certain
conditions. A question mark followed by a single character acts like
an "IF": depending on the following character, a condition is evalu-
ated. If the condition is true, any characters following the question
mark and condition character, up to a period, are included in the
prompt. If the condition is false, such characters are not included.
A colon appearing between the question mark and the period can be used
to establish an "ELSE": any characters between the colon and the period
are included in the string if and only if the IF condition is false.
Condition characters (which follow a question mark) may be:

?a True if any characters have been included in the prompt so far.

?bX True if the byte offset of the specified line is known.

?B True if the size of current input file is known.

?c True if the text is horizontally shifted (%c is not zero).

?dX True if the page number of the specified line is known.

?e True if at end-of-file.

?f True if there is an input filename (that is, if input is not a
pipe).

?lX True if the line number of the specified line is known.

?L True if the line number of the last line in the file is known.

?m True if there is more than one input file.

?n True if this is the first prompt in a new input file.

period, percent, and backslash) become literally part of the prompt.
Any of the special characters may be included in the prompt literally
by preceding it with a backslash.

Some examples:

?f%f:Standard input.

This prompt prints the filename, if known; otherwise the string "Stan-
dard input".

?f%f .?ltLine %lt:?pt%pt\%:?btByte %bt:-...

This prompt would print the filename, if known. The filename is fol-
lowed by the line number, if known, otherwise the percent if known,
otherwise the byte offset if known. Otherwise, a dash is printed.
Notice how each question mark has a matching period, and how the %
after the %pt is included literally by escaping it with a backslash.

?n?f%f .?m(file %i of %m) ..?e(END) ?x- Next\: %x..%t

This prints the filename if this is the first prompt in a file, fol-
lowed by the "file N of N" message if there is more than one input
file. Then, if we are at end-of-file, the string "(END)" is printed
followed by the name of the next file, if there is one. Finally, any
trailing spaces are truncated. This is the default prompt. For refer-
ence, here are the defaults for the other two prompts (-m and -M
respectively). Each is broken into two lines here for readability
only.

?n?f%f .?m(file %i of %m) ..?e(END) ?x- Next\: %x.:
?pB%pB\%:byte %bB?s/%s...%t

?f%f .?n?m(file %i of %m) ..?ltlines %lt-%lb?L/%L. :
byte %bB?s/%s. .?e(END) ?x- Next\: %x.:?pB%pB\%..%t

And here is the default message produced by the = command:

?f%f .?m(file %i of %m) .?ltlines %lt-%lb?L/%L. .
byte %bB?s/%s. ?e(END) :?pB%pB\%..%t

The prompt expansion features are also used for another purpose: if an
environment variable LESSEDIT is defined, it is used as the command to
be executed when the v command is invoked. The LESSEDIT string is
expanded in the same way as the prompt strings. The default value for
LESSEDIT is:

%E ?lm+%lm. %f

Note that this expands to the editor name, followed by a + and the line
number, followed by the file name. If your editor does not accept the
"+linenumber" syntax, or has other differences in invocation syntax,
the LESSEDIT variable can be changed to modify this default.


s -o log files

-k use of lesskey files

-t use of tags files

metacharacters in filenames, such as *

filename completion (TAB, ^L)

Less can also be compiled to be permanently in "secure" mode.


COMPATIBILITY WITH MORE
If the environment variable LESS_IS_MORE is set to 1, or if the program
is invoked via a file link named "more", less behaves (mostly) in con-
formance with the POSIX "more" command specification. In this mode,
less behaves differently in these ways:

The -e option works differently. If the -e option is not set, less
behaves as if the -E option were set. If the -e option is set, less
behaves as if the -e and -F options were set.

The -m option works differently. If the -m option is not set, the
medium prompt is used, and it is prefixed with the string "--More--".
If the -m option is set, the short prompt is used.

The -n option acts like the -z option. The normal behavior of the -n
option is unavailable in this mode.

The parameter to the -p option is taken to be a less command rather
than a search pattern.

The LESS environment variable is ignored, and the MORE environment
variable is used in its place.


ENVIRONMENT VARIABLES
Environment variables may be specified either in the system environment
as usual, or in a lesskey (1) file. If environment variables are
defined in more than one place, variables defined in a local lesskey
file take precedence over variables defined in the system environment,
which take precedence over variables defined in the system-wide lesskey
file.

COLUMNS
Sets the number of columns on the screen. Takes precedence over
the number of columns specified by the TERM variable. (But if
you have a windowing system which supports TIOCGWINSZ or
WIOCGETD, the window system's idea of the screen size takes
precedence over the LINES and COLUMNS environment variables.)

EDITOR The name of the editor (used for the v command).
LANG Language for determining the character set.

LC_CTYPE
Language for determining the character set.

LESS Options which are passed to less automatically.

LESSANSIENDCHARS
Characters which may end an ANSI color escape sequence (default
"m").

LESSANSIMIDCHARS
Characters which may appear between the ESC character and the
end character in an ANSI color escape sequence (default
"0123456789;[?!"'#%()*+ ".

LESSBINFMT
Format for displaying non-printable, non-control characters.

LESSCHARDEF
Defines a character set.

LESSCHARSET
Selects a predefined character set.

LESSCLOSE
Command line to invoke the (optional) input-postprocessor.

LESSECHO
Name of the lessecho program (default "lessecho"). The lessecho
program is needed to expand metacharacters, such as * and ?, in
filenames on Unix systems.

LESSEDIT
Editor prototype string (used for the v command). See discus-
sion under PROMPTS.

LESSGLOBALTAGS
Name of the command used by the -t option to find global tags.
Normally should be set to "global" if your system has the global
(1) command. If not set, global tags are not used.

LESSHISTFILE
Name of the history file used to remember search commands and
shell commands between invocations of less. If set to "-" or
"/dev/null", a history file is not used. The default is
"$HOME/.lesshst" on Unix systems, "$HOME/_lesshst" on DOS and
Windows systems, or "$HOME/lesshst.ini" or "$INIT/lesshst.ini"
on OS/2 systems.

LESSHISTSIZE
The maximum number of commands to save in the history file. The
default is 100.

mand sent to the shell. If LESSMETAESCAPE is an empty string,
commands containing metacharacters will not be passed to the
shell.

LESSOPEN
Command line to invoke the (optional) input-preprocessor.

LESSSECURE
Runs less in "secure" mode. See discussion under SECURITY.

LESSSEPARATOR
String to be appended to a directory name in filename comple-
tion.

LESSUTFBINFMT
Format for displaying non-printable Unicode code points.

LESS_IS_MORE
Emulate the more (1) command.

LINES Sets the number of lines on the screen. Takes precedence over
the number of lines specified by the TERM variable. (But if you
have a windowing system which supports TIOCGWINSZ or WIOCGETD,
the window system's idea of the screen size takes precedence
over the LINES and COLUMNS environment variables.)

PATH User's search path (used to find a lesskey file on MS-DOS and
OS/2 systems).

SHELL The shell used to execute the ! command, as well as to expand
filenames.

TERM The type of terminal on which less is being run.

VISUAL The name of the editor (used for the v command).


COPYRIGHT
Copyright (C) 1984-2007 Mark Nudelman

less is part of the GNU project and is free software. You can redis-
tribute it and/or modify it under the terms of either (1) the GNU Gen-
eral Public License as published by the Free Software Foundation; or
(2) the Less License. See the file README in the less distribution for
more details regarding redistribution. You should have received a copy
of the GNU General Public License along with the source for less; see
the file COPYING. If not, write to the Free Software Foundation, 59
Temple Place, Suite 330, Boston, MA 02111-1307, USA. You should also
have received a copy of the Less License; see the file LICENSE.

For more information, see the less homepage at
http://www.greenwoodsoftware.com/less.