The cat command (short for concatenate) shown in this example is like the DOS type command. In response to the command cat pig_info, the system simply splatters the file on the screen. If there is more data in the file than will fit on one screen, the contents whiz by before you can see it. The more command solves this problem by displaying the file screen by screen:

$ more filename

Source: http://lowfatlinux.com/linux-display-files-cat.html

To adjust the size of your search replace +10000k with the size you desired, such as the following:

• 50MB: +50000k
• 100MB: +100000k
• 500MB: +500000k

find / -type f -size +10000k -exec ls -lh {} \; | awk '{ print $5 ": " $9 }' |sort -n

find . -name filename

Source: http://www.tech-recipes.com/rx/976/unixlinux-easily-find-or-search-files-or-directories/

Received: (qmail 30501 invoked by uid 10077); 3 Dec 2009 21:47:42 -0500
Date: 3 Dec 2009 21:47:42 -0500
Message-ID: <20091204024742.30498.qmail@hostserver.com>
To: email@domain.com
Subject: This is a test.
MIME-Version: 1.0
Content-type: text/html; charset=iso-8859-1
From: <user@domain.com>

It says its invoked by uid 10077 which corresponds to the account on the /etc/password file:

-bash-3.2# more /etc/passwd | grep 10077
username:x:10077:2522::/var/www/vhosts/domain.com:/bin/false

find . -exec grep "www.athabasca" '{}' \; -print

This command will search in the current directory and all sub directories. All files that contain the string will have their path printed to standard output.

Source: http://www.athabascau.ca/html/depts/compserv/webunit/HOWTO/find.htm

killall -9 do_backup

and run it with debugging:

/usr/local/tbackup/do_backup -d

You should see exactly what happens.

tail /usr/local/psa/var/log/maillog -n10000 | grep "user@example.com"

Notes:

Better to tail than cat (in case its a big log)

-n10000 is going back 10000 lines

Add -f if you want to see a live feed of the log

tail -f /usr/local/psa/var/log/maillog | grep "user@example.com"

Source: http://www.woyano.com/view/578/How-to-grep-a-mail-log-to-see-if-a-message-bounced

It displays the file system block usage for each file argument and for each directory in the file hierarchy rooted in each direc tory argument. If no file is specified it will use current directory.

du command Examples

Type du to display usage in current directory :

$ du

Pass -h option to display output in Byte, Kilobyte, Megabyte, Gigabyte, Terabyte and Petabyte (Human-readable output)

$ du -h

Display the name and size of each png file in the /ramdisk/figs/ directory as well as a total for all of the pngs:

$ du -hc /ramdisk/figs/*.png

Another useful option is -c which produce a grand total:

$ du -c

Show the disk usage of the /home/vivek subdirectory:

$ du /home/vivek

Show only a summary of the disk usage of the /home/vivek

$ du -hs /home/vivek

Exclude files that match PATTERN. For example do not count *.obj or *.jpg files:

$ du -h --exclude='*.obj'
$ du -h --exclude='*.jpg'

A PATTERN is a shell pattern (not a regular perl or other expression). The pattern ? matches any one character, whereas * matches any string.

Pipes and filters with du

Now display everything sorted by filesize:

$ du -sk .[A-z]* *| sort -n

Display screenful output at a time as du generate more output than can fit on the console / screen:

$ du -h | less

To find top 3 directories, enter :

$ du -sk * | sort -nr | head -3

4620348 var
651972  home
27896   usr
21384   lib64

Working without du

Finally here is one liner (without du command) that prints top 10 filesize in Mb (thanks to dreyser for submitting idea):

# find /var -type f | xargs ls -s | sort -rn | awk '{size=$1/1024; printf("%dMb %s\n", size,$2);}' | head

Output:

31Mb /var/crash/_usr_lib_firefox_firefox-bin.1000.crash
22Mb /var/cache/apt/archives/linux-image-2.6.20-16-generic_2.6.20-16.28_i386.deb
16Mb /var/lib/apt/lists/in.archive.ubuntu.com_ubuntu_dists_feisty_universe_binary-i386_Packages
15Mb /var/cache/apt/archives/linux-restricted-modules-2.6.20-16-generic_2.6.20.5-16.28_i386.deb
9Mb /var/cache/apt/srcpkgcache.bin
9Mb /var/cache/apt/pkgcache.bin
8Mb /var/cache/apt/archives/firefox_2.0.0.4+1-0ubuntu1_i386.deb
7Mb /var/cache/apt/archives/linux-headers-2.6.20-16_2.6.20-16.28_i386.deb
5Mb /var/lib/apt/lists/archive.ubuntu.com_ubuntu_dists_feisty_main_binary-i386_Packages
5Mb /var/lib/apt/lists/in.archive.ubuntu.com_ubuntu_dists_feisty_universe_source_Sources