All commands

Very useful set of commands to know when your file system was created.

Sometimes, you have a lot of NFS in the server and you can't or shouldn't use umount -a. Whis this command, you only umount the fs related to the 'string'

Replace sed regular expressions with perl patterns on the command line.

The sed equivalent is: echo "sed -e"|sed -e 's/sed -e/perl -pe/'

In addition to a swap partition, Linux can also use a swap file. Some programs, like g++, can use huge amounts of virtual memory, requiring the temporary creation of extra space.

While at the command line of of hosta, scp a file from remote hostb to remote hostc. This saves the step of logging into hostb and then issuing the scp command to hostc.

Simply pass an argument to the script to convert the manual page to a PDF:

This let you know which modules has loaded the Apache server, very useful to know if the mod_rewrite is ready to use.

Note the extra space before the command (I had to put it as an underscore since the website eats up preceding spaces). That's all it takes. Now if you check your history with "$ history", it wont show up.

Great for finding which jar some pesky class is hiding in!

For a python project, sometimes I need to clean all the compiled python files. I have an alias 'rmpyc' to this command. This really saves me a lot of typing and hunting throughout the folders to delete those files.

So you have a web site and you've plastered your significant other's name all over it. But you broke up with them and have some new love in your life. How do you find all those instances of their name and replace them?

If are a Bash user and you are in a directory and need to go else where for a while but don't want to lose where you were, use pushd instead of cd.

cd /home/complicated/path/.I/dont/want/to/forget

pushd /tmp

cd thing/in/tmp

popd (returns you to /home/complicated/path/.I/dont/want/to/forget)

Backups all MySQL databases to individual files. Can be put into a script that grabs current date so you have per day backups.

This gets you your default route programatically, useful for scripts

MySQL: CHARSET from latin1 to utf8

Put it into your sh startup script (I use

alias scpresume='rsync --partial --progress --rsh=ssh'

in bash). When a file transfer via scp has aborted, just use scpresume instead of scp and rsync will copy only the parts of the file that haven't yet been transmitted.

getent allows to get the contents of several databases in their native file format even if they are not actually in /etc. For example, if you are using a LDAP or a DB to authenticate your users, you won't find their info by catting /etc/passwd, but "getent passwd" will concatenate /etc/passwd to the LDAP/DB.

Do it.

This command does a tally of concurrent active connections from single IPs and prints out those IPs that have the most active concurrent connections. VERY useful in determining the source of a DoS or DDoS attack.

Displays a calendar.

Uses the fabulous Hpricot library to parse HTML from Ruby. Extracts all elements of "command' class and displays unescaped text from inside these elements. The following command can help install dependencies (apart from Ruby itself)