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---
format: rst
toc: no
...

=====================================
UNIX Tricks
=====================================

See also `freebsd </software/freebsd-tricks>`_ and 
`debian </software/debian>`_ tricks.

Fork many processes with `xargs`
-----------------------------------
To fork off 10 instances of sleep with incremented lengths, 5 at a time::

    $ seq 10 20 | xargs -n 1 -P 5 sleep

Remapping a Keyboard Key to Meta
-----------------------------------
I like having a Meta key (aka "Windows key") for use with system keyboard
shortcuts (change desktop etc), but some laptop keyboards don't have an extra
button. To remap one of the Alt keys, you need to know it's code: on FreeBSD
6.3 it was: ``Alt_R keysum 0xffea keycode 113``. To get the right mapping under
X11, read the directions in ``/usr/X11R6/lib/X11/xkb/README``. To get the right
mapping under the console, edit ``/usr/share/syscons/keymaps/us.iso.kbd`` and
change 'ralt' to 'meta'.

Figlet
---------------------
figlet is the horizontal banner.

thttpd
---------------

thttpd is a super small/light http web server with almost no features. To 
server up the working directory as cgi to local host, use::

    $ thttpd -p 8080 -h localhost -D

Simple "undelete"
--------------------
This oneliner is useful for recovering recently deleted files from unix
filesystems, assuming you know a reasonably unique string in that file. Change
the -A and -B options (lines of context before and after the unique string) as
appropriate, and go through the output file to clean up the text.

    $ sudo grep "bookmark_bar" --binary-files=text -B 10 -A 1000 /dev/sda5 | tee undeleted_content.txt