Bash Book

README.md

Bash Book

boilerplate-bash.bash

#!/usr/bin/env bash
cat - /dev/fd/3 <<- EOF 3<<- 'EOF'
	#!/usr/bin/env bash
	shopt -s -o errexit nounset noclobber pipefail
	BASH_COMPAT=${BASH_VERSINFO[0]}.${BASH_VERSINFO[1]}
	shopt -s extglob globstar lastpipe patsub_replacement
	APP_ID=$(systemd-id128 new)
EOF
	BOOT_ID=$(systemd-id128 boot-id --app-specific="$APP_ID")
	MACHINE_ID=$(systemd-id128 machine-id --app-specific="$APP_ID")
	# INVOCATION_ID=$(systemd-id128 invocation-id) # For services
	: ${XDG_DATA_HOME:=$HOME/.local/share}
	: ${XDG_CONFIG_HOME:=$HOME/.config}
	: ${XDG_STATE_HOME:=$HOME/.local/state}
	: ${XDG_DATA_DIRS:=/usr/local/share/:/usr/share/}
	: ${XDG_CONFIG_DIRS:=/etc/xdg}
	: ${XDG_CACHE_HOME:=$HOME/.cache}
	: ${XDG_RUNTIME_DIR:=$HOME/.local/state/runtime}
	declare -a TRAP_EXIT=()
	trap 'for A in "${TRAP_EXIT[@]}";do eval "$A";done' EXIT
EOF

is-empty.bash

#!/usr/bin/env bash
# Don't use `! is-empty`, as it will hide errors
is-empty () {
	local A=
	A=$(printf '%s\0' "$@" | find -files0-from - -maxdepth 0 -empty -printf .)
	if (($?)); then return 2; fi 
	[[ $A ]]
}
is-not-empty () {
	local A=
	A=$(printf '%s\0' "$@" | find -files0-from - -maxdepth 0 -not -empty -printf .)
	if (($?)); then return 2; fi 
	[[ $A ]]
}

is-number.bash

#!/usr/bin/env bash
is-number () {
	for n in "$@"; do
		# Specific numbers to avoid locale issues
		if [[ $n != *[!0123456789]* ]]; then
			return 1
		fi
	done
	return 0
}

make-temp.bash

#!/usr/bin/env bash
TEMP=
TRAP_EXIT+=( 'rm -f "$TEMP"' )
TEMP=$(mktemp)

prefix-suffix.bash

#!/usr/bin/env bash
prefix () {
	declare USAGE="${FUNCNAME[0]} [-h] [-0] [--] [ARGS ...]"
	declare NL='\n'
	declare -a READARGS=()
	declare -i OPTIND=1
	while getopts h0 OPT; do
		case "$OPT" in
			'h')printf 'Usage: %s\n' "$USAGE";return;;
			'?')printf 'Usage: %s\n' "$USAGE">&2;return 1;;
			'0')NL='\0';READARGS=(-d $'\0');;
		esac
	done
	shift $((OPTIND - 1))
	while read -r "${READARGS[@]}"; do
		for A; do
			printf "%s$NL" "$A$REPLY"
		done
	done
}

suffix () {
	declare USAGE="${FUNCNAME[0]} [-h] [-0] [--] [ARGS ...]"
	declare NL='\n'
	declare -a READARGS=()
	declare -i OPTIND=1
	while getopts h0 OPT; do
		case "$OPT" in
			'h')printf 'Usage: %s\n' "$USAGE";return;;
			'?')printf 'Usage: %s\n' "$USAGE">&2;return 1;;
			'0')NL='\0';READARGS=(-d $'\0');;
		esac
	done
	shift $((OPTIND - 1))
	while read -r "${READARGS[@]}"; do
		for A; do
			printf "%s$NL" "$REPLY$A"
		done
	done
}

upper-lower.bash

#!/usr/bin/env bash
upper () {
	declare USAGE="${FUNCNAME[0]} [-h] [--]"
	declare -i OPTIND=1
	while getopts h OPT; do
		case "$OPT" in
			'h')printf 'Usage: %s\n' "$USAGE";return;;
			'?')printf 'Usage: %s\n' "$USAGE">&2;return 1;;
		esac
	done
	shift $((OPTIND - 1))
	tr '[:lower:]' '[:upper:]'
}

lower () {
	declare USAGE="${FUNCNAME[0]} [-h] [--]"
	declare -i OPTIND=1
	while getopts h OPT; do
		case "$OPT" in
			'h')printf 'Usage: %s\n' "$USAGE";return;;
			'?')printf 'Usage: %s\n' "$USAGE">&2;return 1;;
		esac
	done
	shift $((OPTIND - 1))
	tr '[:upper:]' '[:lower:]'
}