Installed an mplayer rpm from RPMForge repository (mplayer.i386 1.0-0.40.svn20090711.el5.rf) to my CentOS 5 server. I was setting up a bash script to decode and encode several media files. Everytime mplayer was called from the script, I would get the following useless warnings:

MPlayer SVN-r29417-4.1.2 (C) 2000-2009 MPlayer Team
Can't open joystick device /dev/input/js0: No such file or directory
Can't init input joystick
mplayer: could not connect to socket
mplayer: No such file or directory
Failed to open LIRC support. You will not be able to use your remote control.


It was building up my logs. So I put the following two lines in my mplayer configuration file at /etc/mplayer/mplayer.conf:
nolirc=yes
nojoystick=yes

And like linux magic, the errors on each load disappear.

This problem usually occurs when ls is used with a wildcard, like this:

ls *test* | wc -l

Bash first expands the wildcard expression first, and when that list gets too large, the kernel cannot handle it (a limitation of the kernel). So to fix it, use the find command instead, like this:

find . -name "*test*" | wc -l

Command line

Download all specified extension files from an html page:

wget -r -t1 -N -np -A.mp3 http://google.com/music/audio/

-np dont ascend to parent
-r recursive
-l1 level DONT NEED
-N timestamping
-nd no directories DONT NEED
-t 1 = tries
-H span across hosts

To remove quotas, edit /etc/fstab and remove grpquota,usrquota,
then execute the remount, replacing /home with the name:

mount -o remount /home

Convert unix timestamp to readable format in Bash

date -d @1280565192

Kill multiple processes using grep:

kill -9 `ps aux | grep perl | grep nobody | awk '{print $2}'`

Xargs: handle spaces and punctuation properly:

xargs -0

Using ack and sed, edit files in place

sed -i 's/replacestring/replacedwiththis/g' `~/bin/ack --php "searchstring" -l`

Rename doesn’t support renaming with a dash/hyphen, so we must use this forloop/mv hack:

for i in ./*foo*;do mv -- "$i" "${i//test test2/test - test2}";done

Find Command

COPY files less than 24 hours old to /some/other/directory

find . -type f -ctime -1 | xargs -I {} cp {} /some/other/directory

MOVE files less than 24 hours old to /some/other/directory

find . -type f -ctime -1 | xargs -I {} mv {} /some/other/directory

Scan files for certain text

find dir/ -name "*.txt" -exec grep -Hn "md5_func" {} \;

Find all directories and sub-directories that are empty.

find ./ -type d -empty

MySQL

Using mysql from command line, here’s how to save results to an outfile (in interactive mode):

SELECT * INTO outfile '/tmp/sql.out' FROM tablename WHERE condition  = '1';

Using mysql from command line, here’s how to save resultset to an outfile (using a sql file):

mysql database -u username -p < batch.sql > sql.out