1. Show/purge unused linux kernel images and modules:

dpkg -l 'linux-*' | sed '/^ii/!d;/'"$(uname -r | sed "s/\(.*\)-\([^0-9]\+\)/\1/")"'/d;s/^[^ ]* [^ ]* \([^ ]*\).*/\1/;/[0-9]/!d'

If you use sudo to run commands as root, you've probably run into “permission denied” problems when only part of a pipeline or part of a command is running with root permissions.

Eight must-know Linux commands that will turn any Linux novice into an apparent command line guru. Go on. Impress your friends and family.

In this context, a one-liner is a set of commands normally joined through a pipe (|). When joined by a pipe, the command on the left passes its output to the command on the right. Simple or complex, you can get useful results from a single line at the bash command prompt.

Today we have a simple tip of the shell. Are there applications or scripts that you use that require different environment variables, such as a different PATH or EDITOR? Then meet the env command. env allows you to run a program in a restricted environment with custom variables or so that no “dirty” variables are left around.

One of the best features in Linux is the way you can control processes from the command line, so if you have an application that locks up your GUI, you can always SSH over from another machine and just kill the offending process.

Perhaps your company is just switching to Linux, to save on costs. Or, maybe you’re starting University, and you have no idea how to get around the Linux Systems they’ve just installed. Or if you’re like me, you’re curious about how Linux works, and you have it installed at home.

Yesterday’s post detailed how you can find files by their name, permissions, time, or other descriptors. But you probably also want to be able to find files based on what is inside them. Grep is a tool that picks up where find left off, and can search inside files (though cannot do the same things that find can).