Commands by ptotaram (1)

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Release memory used by the Linux kernel on caches
=1 --> to free pagecache =2 --> to free dentries and inodes =3 --> to free pagecache, dentries and inodes

Remove all unused kernels with apt-get
A little aptitude magic. Note: this will remove images AND headers. If you just want to remove images: aptitude remove ?and(~i~nlinux-im ?not(~n`uname -r`)) I used this in zsh without any problems. I'm not sure how other shells will interpret some of the special characters used in the aptitude search terms. Use -s to simulate.

Create a persistent connection to a machine
Create a persistent SSH connection to the host in the background. Combine this with settings in your ~/.ssh/config: Host host ControlPath ~/.ssh/master-%r@%h:%p ControlMaster no All the SSH connections to the machine will then go through the persisten SSH socket. This is very useful if you are using SSH to synchronize files (using rsync/sftp/cvs/svn) on a regular basis because it won't create a new socket each time to open an ssh connection.

Using tput to save, clear and restore the terminal contents
Very useful for interactive scripts where you would like to return the terminal contents to its original state before the script was run. This would be similar to how vi exits and returns you to your original terminal screen. Save and clear the terminal contents with: $tput smcup Execute some commands, then restore the saved terminal contents with: $tput rmcup

Print text string vertically, one character per line.

identify NEEDED sonames in a path
This works in combination with http://www.commandlinefu.com/commands/view/10496/identify-exported-sonames-in-a-path as it reports the NEEDED entries present in the files within a given path. You can then compare it with the libraries that are exported to make sure that, when cross-building a firmware image, you're not bringing in dependencies from the build host. The short version of it as can be seen in the same output is $ scanelf -RBnq -F "+n#f" $1 | tr ',' '\n' | sort -u

Find files of two different extensions and copy them to a directory

Watch Al Jazeera Livestream directly in mplayer #jan25
One cannot call the high quality livestream directly, but command this gives you a session ID and the high quality stream. #egypt #jan25

Re-emerge all ebuilds with missing files (Gentoo Linux)

Doing some floating point calculations with rounding (e.g. at the 3rd decimal)


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