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Bash also supports functions. Add the functions to ~/.bashrc, or a separate file which is sourced from ~/.bashrc. More Bash function examples can be found in BBS#30155.

Display error codes

To set trap to intercept a non-zero return code of the last program run:

EC() {
	echo -e '\e[1;33m'code $?'\e[m\n'
trap EC ERR

Compile and execute a C source on the fly

The following function will compile (within the /tmp/ directory) and execute the C source argument on the fly (and the execution will be without arguments). And finally, after program terminates, will remove the compiled file.

# Compile and execute a C source on the fly
csource() {
	[[ $1 ]]    || { echo "Missing operand" >&2; return 1; }
	[[ -r $1 ]] || { printf "File %s does not exist or is not readable\n" "$1" >&2; return 1; }
	local output_path=${TMPDIR:-/tmp}/${1##*/};
	gcc "$1" -o "$output_path" && "$output_path";
	rm "$output_path";
	return 0;


The following function will extract a wide range of compressed file types. and use it with the syntax extract <file1> <file2> ...

extract() {
    local c e i

    (($#)) || return

    for i; do

        if [[ ! -r $i ]]; then
            echo "$0: file is unreadable: \`$i'" >&2

        case $i in
                   c=(bsdtar xvf);;
            *.7z)  c=(7z x);;
            *.Z)   c=(uncompress);;
            *.bz2) c=(bunzip2);;
            *.exe) c=(cabextract);;
            *.gz)  c=(gunzip);;
            *.rar) c=(unrar x);;
            *.xz)  c=(unxz);;
            *.zip) c=(unzip);;
            *)     echo "$0: unrecognized file extension: \`$i'" >&2

        command "${c[@]}" "$i"
        ((e = e || $?))
    return "$e"
Note: Make sure extglob is enabled: shopt -s extglob, by adding it to the ~/.bashrc (see gregswiki:glob#Options_which_change_globbing_behavior).

Another way to do this is to install a specialized package, see Archiving and compression tools#Convenience tools.

cd and ls in one

Very often changing to a directory is followed by the ls command to list its contents. Therefore it is helpful to have a second function doing both at once. In this example we will name it cl (change list) and show an error message if the specified directory does not exist.

cl() {
	local dir="$1"
	local dir="${dir:=$HOME}"
	if [[ -d "$dir" ]]; then
		cd "$dir" >/dev/null; ls
		echo "bash: cl: $dir: Directory not found"

Of course the ls command can be altered to fit your needs, for example ls -hall --color=auto.

Simple note taker

note () {
    # if file doesn't exist, create it
    if [[ ! -f $HOME/.notes ]]; then
        touch "$HOME/.notes"

    if ! (($#)); then
        # no arguments, print file
        cat "$HOME/.notes"
    elif [[ "$1" == "-c" ]]; then
        # clear file
        printf "%s" > "$HOME/.notes"
        # add all arguments to file
        printf "%s\n" "$*" >> "$HOME/.notes"

Simple task utility

Inspired by #Simple note taker

todo() {
    if [[ ! -f $HOME/.todo ]]; then
        touch "$HOME/.todo"

    if ! (($#)); then
        cat "$HOME/.todo"
    elif [[ "$1" == "-l" ]]; then
        nl -b a "$HOME/.todo"
    elif [[ "$1" == "-c" ]]; then
        > $HOME/.todo
    elif [[ "$1" == "-r" ]]; then
        nl -b a "$HOME/.todo"
        eval printf %.0s- '{1..'"${COLUMNS:-$(tput cols)}"\}; echo
        read -p "Type a number to remove: " number
        sed -i ${number}d $HOME/.todo "$HOME/.todo"
        printf "%s\n" "$*" >> "$HOME/.todo"


calc() {
    echo "scale=3;$@" | bc -l


Kingbash - menu driven auto-completion (see BBS#101010).

Install kingbash-gb-gitAUR from the AUR, then insert the following into your ~/.bashrc:

function kingbash.fn() {
    echo -n "KingBash> $READLINE_LINE" #Where "KingBash> " looks best if it resembles your PS1, at least in length.
    OUTPUT=$(/usr/bin/kingbash "$(compgen -ab -A function)")
    READLINE_POINT=$(echo "$OUTPUT" | tail -n 1)
    READLINE_LINE=$(echo "$OUTPUT" | head -n -1)
    echo -ne "\r\e[2K"
bind -x '"\t":kingbash.fn'

IP info

Detailed information on an IP address or hostname in bash via

ipif() { 
    if grep -P "(([1-9]\d{0,2})\.){3}(?2)" <<< "$1"; then
	ipawk=($(host "$1" | awk '/address/ { print $NF }'))
Note: Bash is limited to extended regular expressions; this example uses perl regular expressions with grep. [1]