267 lines
6.7 KiB
Bash
Executable File
267 lines
6.7 KiB
Bash
Executable File
#!/usr/bin/env bash
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## rdlink [-d|--debug] <PATH>
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##
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## License: GNU GPL V3 or later
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## Author: Martin Winkler
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# Exit on error. Append "|| true" if you expect an error.
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set -o errexit
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# Exit on error inside any functions or subshells.
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set -o errtrace
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# Do not allow use of undefined vars. Use ${VAR:-} to use an undefined VAR
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set -o nounset
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# Catch the error in case mysqldump fails (but gzip succeeds) in `mysqldump |gzip`
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set -o pipefail
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LOG_LEVEL="${LOG_LEVEL:-1}" # 7 = debug -> 0 = emergency
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rl::rdlink() {
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local subject=
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local work=
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local resolved=0
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info "Processing: $@"
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info " with pwd: $(pwd)"
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subject="$(rl::cleanpath "${1:-}")" || true
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# Follow multiple symlinks
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while subject="$(rl::quicklink "${subject}")" ; do
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# A link was resolved at least once
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info "rl::rdlink - Link found: $subject"
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resolved=1
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done
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# Special cases handling
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{
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# If subject is still a link, after rl::quicklink call(s)
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# current user has no permission to access the link itself
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# (e.g. /proc/**/cwd)
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if [ -L "${subject}" ] ; then
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info "rl::rdlink exit - can't access link ${subject}"
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printf "\n"
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return 1
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fi
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}
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# Empty output if (dirname $subject) is not a valid path
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if ! work="$(rl::canon "${subject}")" ; then
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# Special: Links resolved to something like: /proc/2267178/fd/pipe:[22306727]
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# are not existing files but `readlink -f` prints result anyway
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# Printing result if a link was resolved at least once
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#if (( ! resolved )); then
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info "rl::rdlink exit - invalid path ${work}"
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printf "\n"
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return 1
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#fi
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else
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subject="${work}"
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fi
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printf "${subject}\n"
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}
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rl::quicklink() {
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subject=
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work=
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info "Quicklink... ${1:-}"
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# Check if current candidate is a symlink
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if ! subject=$(readlink -- "${1:-}"); then
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printf -- "${1:-}\n"
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return 1
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fi
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info " - symlink ${1} -> ${subject}"
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# relative symlink target; prepend its parent direcotry
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if [[ "${subject}" != "/"* ]]; then
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work="$(rl::canon "$(dirname -- "${1:-}")")"
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subject="${work}/${subject}"
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info " - relative link resolved: ${subject}"
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fi
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printf "${subject}\n"
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return 0
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}
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rl::canon() {
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local subject=
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local work=
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local bname=
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local run=1
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local start=
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local retval=0
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start="${1:-}"
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info "Canonicalize path... ${start}"
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while (( run )) ; do
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if work="$(cd "${start}" >/dev/null 2>&1 && pwd -P)" ; then
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# Special: `pwd -P` returns with // as root for links starting at /
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# e.g. $(readlink /proc/self/root) == "/"
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# $(cd /proc/self/root/mnt && pwd -P) == "//mnt"
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subject="$(rl::normalize "${work}")"
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info "rl::canon valid directory: ${subject}"
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run=0
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elif work="$(cd "$(dirname -- "${start}")" >/dev/null 2>&1 && pwd -P)" ; then
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bname="$(basename -- "${start}")"
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# Special: / produces //
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[[ "${work}" == "/" ]] && work=
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subject="${work}${bname:+"/${bname}"}"
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info "rl::canon valid parent: ${subject}"
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# Special: Succeed with valid element after second run; see special below
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# e.g. /root/.
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# * /root is valid but not accessible
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if (( retval )) && [ -e "${subject}" ] ;then
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info "rl::canon valid element"
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retval=0
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fi
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run=0
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else
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# Special: Some paths may be resolvable after normalization
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# e.g. somedir/..
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# * base "somedir" does not exist
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# * but irrelevant because of /..
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# * resolves to pwd but fails by readlink -f
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work="$(rl::normalize "${start}")"
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if [[ "${work}" != "${start}" ]] ; then
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info "rl::canon retry with: ${work}"
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start="${work}"
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retval=1
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continue
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fi
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info "rl::canon invalid path: ${work}"
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subject="${work}"
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run=0 && retval=1
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fi
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done
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printf -- "${subject}\n"
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return ${retval}
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}
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rl::cleanpath() {
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local work=
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local rex_tmp=
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info "Cleaning path... ${1:-}"
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work="${1:-}"
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# Remove multiple /
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while [[ "${work:-}" = *"//"* ]]; do
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work="${work//'//'/'/'}"
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done
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info "rl::cleanpath result: ${work}"
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printf -- "${work}\n"
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}
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rl::normalize() {
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local work=
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info "Normalizing path... ${1:-}"
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work="${1:-}"
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# Remove dir/.. sequences.
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local rex_tmp='[^/][^/]*/\.\./*'
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while [[ "${work}" =~ $rex_tmp ]] ; do
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work="${work/"${BASH_REMATCH[0]}"/}"
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done
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# Remove /./ and /.$ sequences.
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rex_tmp='/\.(/|$)'
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while [[ "$work" =~ $rex_tmp ]]; do
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work="${work/"${BASH_REMATCH[0]}"/"${BASH_REMATCH[1]/$//}"}"
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done
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# Remove leading ./
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work="${work#./*}"
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# Remove trailing /
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rex_tmp='(.*[^/])/$'
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if [[ "${work}" =~ $rex_tmp ]] ; then
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work="${BASH_REMATCH[1]}"
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fi
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info "rl::normalize result: ${work}"
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printf -- "${work}\n"
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}
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rl::main() {
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local file=
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local arg=
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for arg in "$@"; do
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case "$arg" in
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--)
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shift
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break ;;
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-d|--debug)
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shift
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LOG_LEVEL=7 ;;
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-dd)
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shift
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set -o xtrace ;;
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-*)
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shift ;;
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esac
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done
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info "BASH rdlink"
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for file in "$@"; do
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rl::rdlink "$file"
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done
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}
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function rl::log () {
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local log_level="${1:-${LOG_LEVEL}}"
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shift
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# all remaining arguments are to be printed
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local log_line=""
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while IFS=$'\n' read -r log_line; do
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printf "%s [%9s] %s\n" "$(date -u +"%Y-%m-%d %H:%M:%S UTC")" "${log_level}" "${log_line}" 1>&2
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done <<< "${@:-}"
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}
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emergency() { rl::log emergency "${@}"; exit 1; }
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alarm() { [[ "${LOG_LEVEL:-0}" -ge 1 ]] && rl::log alert "${@}"; true; }
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critical() { [[ "${LOG_LEVEL:-0}" -ge 2 ]] && rl::log critical "${@}"; true; }
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error() { [[ "${LOG_LEVEL:-0}" -ge 3 ]] && rl::log error "${@}"; true; }
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warning() { [[ "${LOG_LEVEL:-0}" -ge 4 ]] && rl::log warning "${@}"; true; }
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notice() { [[ "${LOG_LEVEL:-0}" -ge 5 ]] && rl::log notice "${@}"; true; }
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info() { [[ "${LOG_LEVEL:-0}" -ge 6 ]] && rl::log info "${@}"; true; }
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debug() { [[ "${LOG_LEVEL:-0}" -ge 7 ]] && rl::log debug "${@}"; true; }
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msg() { echo "$@"; true; }
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# Provide as function to be called when sourced
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rdlink() {
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rl::rdlink "$@"
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}
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### Check if script is _sourced
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### https://stackoverflow.com/a/28776166
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_sourced=0
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if [ -n "${ZSH_EVAL_CONTEXT:-}" ]; then
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case ${ZSH_EVAL_CONTEXT:-} in *:file) _sourced=1;; esac
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elif [ -n "${KSH_VERSION:-}" ]; then
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[ "$(cd $(dirname -- $0) && pwd -P)/$(basename -- $0)" != "$(cd $(dirname -- ${.sh.file}) && pwd -P)/$(basename -- ${.sh.file})" ] && _sourced=1
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elif [ -n "${BASH_VERSION:-}" ]; then
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(return 0 2>/dev/null) && _sourced=1
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else # All other shells: examine $0 for known shell binary filenames
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# Detects `sh` and `dash`; add additional shell filenames as needed.
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case ${0##*/} in sh|dash) _sourced=1;; esac
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fi
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###
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if (( ! _sourced )); then
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rl::main "$@"
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fi
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