Bash/Functions

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.

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

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ドル ]] || { echo "Missing operand" >&2; return 1; }
	[[ -r 1ドル ]] || { printf "File %s does not exist or is not readable\n" "1ドル" >&2; return 1; }
	local output_path=${TMPDIR:-/tmp}/${1##*/};
	gcc "1ドル" -o "$output_path" && "$output_path";
	rm "$output_path";
	return 0;
}

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

extract() {
 local c e i
 (($#)) || return
 for i; do
 c=''
 e=1
 if [[ ! -r $i ]]; then
 echo "0ドル: file is unreadable: \`$i'" >&2
 continue
 fi
 case $i in
 *.t@(gz|lz|xz|b@(2|z?(2))|a@(z|r?(.@(Z|bz?(2)|gz|lzma|xz|zst)))))
 c=(bsdtar xvf);;
 *.7z) c=(7z x);;
 *.Z) c=(uncompress);;
 *.bz2) c=(bunzip2);;
 *.exe) c=(cabextract);;
 *.gz) c=(gunzip);;
 *.rar) c=(unrar x);;
 *.xz) c=(unxz);;
 *.zip) c=(unzip);;
 *.zst) c=(unzstd);;
 *) echo "0ドル: unrecognized file extension: \`$i'" >&2
 continue;;
 esac
 command "${c[@]}" "$i"
 ((e = e || $?))
 done
 return "$e"
}

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

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

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

note () {
 # if file doesn't exist, create it
 if [[ ! -f $HOME/.notes ]]; then
 touch "$HOME/.notes"
 fi
 if ! (($#)); then
 # no arguments, print file
 cat "$HOME/.notes"
 elif [[ "1ドル" == "-c" ]]; then
 # clear file
 printf "%s" > "$HOME/.notes"
 else
 # add all arguments to file
 printf "%s\n" "$*" >> "$HOME/.notes"
 fi
}

Inspired by #Simple note taker

todo() {
 if [[ ! -f $HOME/.todo ]]; then
 touch "$HOME/.todo"
 fi
 if ! (($#)); then
 cat "$HOME/.todo"
 elif [[ "1ドル" == "-l" ]]; then
 nl -b a "$HOME/.todo"
 elif [[ "1ドル" == "-c" ]]; then
 > $HOME/.todo
 elif [[ "1ドル" == "-r" ]]; then
 nl -b a "$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"
 else
 printf "%s\n" "$*" >> "$HOME/.todo"
 fi
}

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

Detailed information on an IP address or hostname in bash via https://ipinfo.io:

ipif() { 
 if grep -P "(([1-9]\d{0,2})\.){3}(?2)" <<< "1ドル"; then
	 curl ipinfo.io/"1ドル"
 else
	ipawk=($(host "1ドル" | awk '/address/ { print $NF }'))
	curl ipinfo.io/${ipawk[1]}
 fi
 echo
}

List folders sorted by size, showing the largest first. A helper where to start cleaning when the disk is full. Use it with the syntax whatsize directory or just whatsize to list the / directory sizes.

whatsize(){
 du -h --max-depth=1 --exclude=/{proc,sys,dev,run} -t 1 ${1:-/} 2>/dev/null | sort -hr
}

• Command-line shells