Computer Music Politics Miscellany

BASH Tricks

The following are some bash usage examples. They are not organized because they are meant to be accessed by links from other documentation. Think of them as a collection of footnotes.


Command substitution.

`command` or $(command) substitutes the standard output of command. In the following example the process with the pid found in the file /var/run/ppp0.pid is killed if the process id was placed in the file.

    kill `cat /var/run/ppp0.pid`

The next example demonstrates how to substitute the current kernel version number into a path:

    /lib/modules/`uname -r`/modules.dep

The current kernel version is substituted for `uname -r` and the path to modules.dep is completed. The resulting path would look something like this:

    /lib/modules/2.2.16/modules.dep

(Note: ` and ' are different characters. The character ' will not work for command substitution.)


Function definitions

function name () { list; } or name () { list; } defines a function called name and will execute whatever is in list. If you want to define a function to view the contents of a tar ball called myfile.tar.gz type the following

    tart () { tar tzvf $1; }

at the command line; then type “tart myfile.tar.gz” and you will have a list of the contents of the tar ball. To have the function available all the time simply add the definition to your ~/.profile or ~/.bashrc file.

Last updated: Saturday, 13-Sep-2014 01:47:37 UTC