Linux commands that prove useful for your day to day workflow.

Posted: February 16, 2012. At: 9:59 PM. This was 6 years ago. Post ID: 2745

The UNIX tail command is very useful for viewing the last number of lines of a logfile.

As in this example. Showing the last 10 lines in the file /var/log/syslog.

|{~}-{Thu Feb 16 21:36:44}
[email protected] } $ tail -n 10 /var/log/syslog
Feb 16 21:31:01 deep-thought cron[1480]: (*system*anacron) WRONG FILE OWNER (/etc/cron.d/anacron)
Feb 16 21:31:29 deep-thought kernel: [34739.919485] device eth0 entered promiscuous mode
Feb 16 21:31:47 deep-thought kernel: [34758.095250] device eth0 left promiscuous mode
Feb 16 21:31:53 deep-thought kernel: [34764.193301] vboxnetflt: dropped 0 out of 7 packets
Feb 16 21:31:58 deep-thought kernel: [34769.069486] device eth0 entered promiscuous mode
Feb 16 21:32:01 deep-thought cron[1480]: (*system*anacron) WRONG FILE OWNER (/etc/cron.d/anacron)
Feb 16 21:33:01 deep-thought cron[1480]: (*system*anacron) WRONG FILE OWNER (/etc/cron.d/anacron)
Feb 16 21:34:01 deep-thought cron[1480]: (*system*anacron) WRONG FILE OWNER (/etc/cron.d/anacron)
Feb 16 21:35:01 deep-thought cron[1480]: (*system*anacron) WRONG FILE OWNER (/etc/cron.d/anacron)
Feb 16 21:36:01 deep-thought cron[1480]: (*system*anacron) WRONG FILE OWNER (/etc/cron.d/anacron)

The head(1) command will show the first ten lines in the file.

[email protected] } $ head -n 10 /var/log/dmesg
[    0.000000] Initializing cgroup subsys cpuset
[    0.000000] Initializing cgroup subsys cpu
[    0.000000] Linux version 3.2.5-custom ([email protected]) (gcc version 4.6.2 (Ubuntu/Linaro 4.6.2-12ubuntu1) ) #1 SMP PREEMPT Tue Feb 7 21:54:11 EST 2012
[    0.000000] KERNEL supported cpus:
[    0.000000]   Intel GenuineIntel
[    0.000000]   AMD AuthenticAMD
[    0.000000]   NSC Geode by NSC
[    0.000000]   Cyrix CyrixInstead
[    0.000000]   Centaur CentaurHauls
[    0.000000]   Transmeta GenuineTMx86

I have also included some useful information here: http://www.securitronlinux.com/bejiitaswrath/using-redirection-on-the-command-unix-command-line/ discussing various tricks using redirection on the Linux command line.

Searching for a certain filename in your home folder. The locate command comes into its own for this when you need to find a certain file amongst all of the clutter that accumulates in your home directory.

|{~}-{Thu Feb 16 21:45:57}
[email protected] } $ locate freedoom
/home/thx/Doom2/freedoom.wad
/home/thx/Doom2/freedoomult.wad
/home/thx/Downloads/freedoom-iwad-latest.zip
/usr/share/app-install/desktop/freedoom:freedoom.desktop
/usr/share/app-install/icons/freedoom.png
/usr/share/games/freedoom
/usr/share/games/freedoom/freedm.wad

As seen in this example, I am searching for the freedoom wadfiles I have on my hard drive and I had forgotten where they were.

Generating a tree view in HTML of the current folder and subfolders.

|{~/Documents/CHASM}-{Thu Feb 16 21:55:03}
[email protected] } $ /usr/bin/tree -R -H ./

There are some more useful commands here: http://securitron.securitronlinux.com/linux_configs.php.

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