Linux General

Tips -N- Tricks

Truncating a File

If you want to empty a file quickly (like purging a log file) then run the following command:

:> filename

Search command history

grep -i 'SearchStringHere' ~/.bash_history

View Log Continuously

tail -f /path/to/log/filename

or

Filter a continuous log for a specific entry

tail -f /path/to/log/filename | grep -i 'FilterStringHere'

Dump a .conf file to a new file without the comments (#)

grep -v '#' file.conf > newfile.conf

Disable/Enable Swap

To disable all swap space in Linux use this command:

swapoff -a

To re-enable it use this command:

swapon -a

Run a command as a different User

su <SOME_OTHER_USER>

or Run as a user that doesn't have shell access (Like the 'www' account).

su -m www -c "run some command here"

Note: The -c option is used to run a single command.

RPM's

RedHat based distributions use RPM's short for Redhat Package Manager. To view a list of installed RPMS:

rpm -qa

To look for a specific installed package:

rpm -qa | grep 'package_name'

To view the contents of a RPM

rpm -qpil /path/to/package.rpm

Common Sqitches: -i Install
-U Upgrade
-v verbose
-h Display Hash mark progress bar
-e erase
--force forces an erase or upgrade