All commands

trap is the bash builtin that allows you to execute commands when the current script receives a particular signal.

Uses $0 for the script name, $$ for the script PID, tee to output to STDOUT as well as a log file and ps to log other running processes.

available timezone can be found in /usr/share/zoneinfo. Other examples:

this is based on zoneinfo files on macosx. Your mileage my vary on other unix dialects

You can exclude more system folders or individual files which are not necessary for the backup and can be recreated after the restore procedure, like /lost+found, /mnt, /media, /tmp, /usr ...

Restoring the above backup procedure is as simple as becoming root and typing:

You can extract any file or directory out of the backup.tgz file for recovery, for instance, if you have a corrupt or mis-configured fstab file, you could simply issue the command:

Other options:

v add verbose option to see files processed

A far safer solution is to restore the desired files under a different directory, and then compare, move, or update the files to their original locations afterward.

Using the redundant ./ directory information prevents the dash from occurring at the beginning of the filename, and being interpreted as an option of the rm command.

Also works using:

This will print to the screen password for the user specified in "sys_users.login='xxxx';. This is for Plesk servers only.

Alrighty, so I was really bored ;)

Lifted from http://linux.spiney.org/remote_diff_with_vim_and_ssh which points out credits for the inspiration.

unsets variables used by the one-liner

sets up the IFS bash variable to not be affected by whitespace and disables extra glob expansion

uses read to slurp the results of the find command into an array

selects an element of the array at random to be passed as an argument to mplayer

This command takes the output of the 'last' command, removes empty lines, gets just the first field ($USERNAME), sort the $USERNAMES in reverse order and then gives a summary count of unique matches.

Insert a comma where necessary when counting large numbers. I needed to separate huge amounts of packets and after 12+ hours of looking in a terminal, I wanted it in readable form.

(WARN) This will absolutely not work on all systems, unless you're running large, high speed, hardware RAID arrays. For example, systems using Dell PERC 5/i SAS/SATA arrays. If you have a hardware RAID array, try it. It certainly wont hurt.

You may be can test the speed disk with some large file in your system, before and after using this:

To know the value of block device parameter known as readahead.

And set the a value 1024, 2048, 4096, 8192, and maybe 16384... it really depends on the number of hard disks, their speed, your RAID controller, etc. (see sample)

Sometimes, in a shell script, you need a random number bigger than the range of $RANDOM. This will print a random number made of four hex values extracted from /dev/urandom.

I put this in a shell script called "svndiff", as it provides a handy decorated "svn diff" output that is colored (which you can't see here) and paged. The -r is required so less doesn't mangle the color codes.

Blacklisted is a compiled list of all known dirty hosts (botnets, spammers, bruteforcers, etc.) which is updated on an hourly basis. This command will get the list and create the rules for you, if you want them automatically blocked, append |sh to the end of the command line. It's a more practical solution to block all and allow in specifics however, there are many who don't or can't do this which is where this script will come in handy. For those using ipfw, a quick fix would be {print "add deny ip from "$1" to any}. Posted in the sample output are the top two entries. Be advised the blacklisted file itself filters out RFC1918 addresses (10.x.x.x, 172.16-31.x.x, 192.168.x.x) however, it is advisable you check/parse the list before you implement the rules

Searching for a String in Multiple Files With Grep

Locate broken symlinks in the current directory. Also useful, to remove broken links:

I used this to cut down the file size of a 1gb .avi to about 200mb without sacrificing much quality.

Test your XFS filesystem and Raptor hard drives for write performance.

Test your XFS filesystem and Raptor hard drives for write performance.

List only hidden files (or directories). You also can use:

Would be better if gnome-open would accept std in

Should be doable in KDE - anyone?

Sees if two records differ in their entries, irrespective of order.