Bash Shell Skills

Execute GUI Programs

Execute GUI programs in background mode from terminal, and suppresses stdout and stderr.

(gui_program &>/dev/null &)

gui_program is the command you’d like to execute for the GUI program.

You can also add the following code to ~/.bash_aliases:

function xexec(){
	($@ &>/dev/null &)
}
complete -cf xexec

The use command xexec gui_program arguments to execute GUI programs in background mode from terminal with stdout and stderr suppressed.

Extract basename and extension

BASENAME="${FILENAME%.*}";
EXTENSION="${FILENAME##*.}";

Enumerate lines from stdin

IFS=$'\n';
for LINE in `ls`; do
	#Do some works on "${LINE}"
done;

Enumerate command line arguments with space characters

while [ -n "${1}" ]; do
	FILENAME="${1}";
	#Do some works on "${FILENAME}"
	shift 1;
done;

Batch Renaming Using Perl’s Rename Utility

Remove .bak extension:

prename 's/\.bak$//' *

Convert filenames into lower case:

prename 'y/A-Z/a-z/' *

Add prefix for .txt files:

prename 's/(.*).txt$/prefix_$1.txt/' *.txt

On ArchLinux, you must install package perl-rename for this utility.

Find out text files with BOM header

Use find command and file command:

find . -type f -exec file {} \; | grep BOM

Use grep command under bash shell:

grep -rlI $'^\xEF\xBB\xBF' .

Exclude files with given extension (Useful to skip binary files and large files):

grep -rlI $'^\xEF\xBB\xBF' --exclude=*.bin --exclude=*.dat .
find . -type f -not \( -ipath '*.bin' -o -ipath '*.dat' \) -exec file {} \; | grep BOM

Exclude .svn directory:

grep -rlI $'^\xEF\xBB\xBF' --exclude-dir=.svn .
find . -type f -not \( -ipath '*.svn*' \) -exec file {} \; | grep BOM

Convert video into HTML5 compatible format

ffmpeg -i INPUT_FILE -c:v libx264 -crf 18 -c:a aac -q:a 100 -strict experimental OUTPUT.mp4

Adjust Tab Size For VIM

Add the following lines to /etc/vim/vimrc:

set tabstop=4
set softtabstop=4
set shiftwidth=4

Backup file with gzip compression and date suffix

gzip -kS ".$(date '+%Y%m%d_%H%M').gz" backup_file