runbg regenerate.
- make use of journald - avoid command once invoke being triggered twice (or even more).
This commit is contained in:
360
bin/runbg
360
bin/runbg
@@ -6,49 +6,47 @@
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PATH=$(zsh -c -i 'echo $PATH')
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export PATH
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# start-bg.sh - robustly start a command in the background and redirect stdout+stderr to a log
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# Generated by GitHub Copilot.
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# start-bg-journal.sh - start a command as a detached daemon and send stdout/stderr to systemd-journald
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#
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# Features:
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# - Uses setsid (preferred) to detach from the controlling terminal.
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# - Falls back to nohup if setsid is unavailable.
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# - Runs the command with stdin closed, stdout+stderr redirected to a logfile.
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# - Sets a safe umask and changes to / to avoid blocking filesystems.
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# - Writes a pidfile next to the log for easy management.
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# - Uses positional args ($@), script PID ($$) and reports child PID ($!).
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# - Sends stdout+stderr to journald using systemd-cat when available.
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# - Falls back to writing into a logfile if systemd-cat isn't present or if --log is passed.
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# - Uses setsid to detach, closes inherited file descriptors (best-effort),
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# redirects stdin to /dev/null, and execs the target command.
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# - Supports PID file, umask, and a syslog identifier (tag) and priority for journald.
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# - Uses positional args ($@) for the command; uses $$ in auto-generated names and prints the child PID ($!).
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#
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# Usage:
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# start-bg.sh [ -l LOGFILE | -d LOGDIR ] [ -m METHOD ] -- command [args...]
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#
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# Options:
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# -l, --log LOGFILE Path to log file (if omitted an auto name is used)
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# -d, --dir LOGDIR Directory for autogenerated logs (default: ./logs)
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# -m, --method METHOD Background method: setsid (default) | nohup
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# -h, --help Show this help and exit
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# start-bg-journal.sh [ -t TAG ] [ -r PRIORITY ] [ -l LOGFILE | -d LOGDIR ] [ -p PIDFILE ] [ -u UMASK ] -- command [args...]
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#
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# Examples:
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# ./start-bg.sh -- sleep 60
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# ./start-bg.sh -d /var/log/myapp -- /usr/bin/myapp --config /etc/myapp.conf
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# ./start-bg.sh -l ./my.log -- /usr/bin/myapp arg1 arg2
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# ./start-bg-journal.sh -t myapp -- /usr/bin/myapp --config /etc/myapp.conf
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# ./start-bg-journal.sh -l ./my.log -- /usr/bin/myapp arg1 arg2
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# ./start-bg-journal.sh -p /run/myapp.pid -t myapp -r info -- /usr/bin/myapp
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set -euo pipefail
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progname=$(basename "$0")
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usage() {
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cat <<EOF
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Usage: $progname [ -l LOGFILE | -d LOGDIR ] [ -m METHOD ] -- command [args...]
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Usage: $progname [ -t TAG ] [ -r PRIORITY ] [ -l LOGFILE | -d LOGDIR ] [ -p PIDFILE ] [ -u UMASK ] -- command [args...]
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Start "command [args...]" detached from the terminal and redirect stdout+stderr to a log.
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Start command [args...] as a background daemon, sending stdout+stderr to systemd-journald (via systemd-cat)
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when available. If systemd-cat is not available or if -l/--log is provided, logs are written to a logfile.
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METHOD:
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setsid - use setsid to start a session and detach (preferred)
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nohup - use nohup (fallback/compat)
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Options:
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-t, --tag TAG Tag / SYSLOG_IDENTIFIER used by systemd-cat (default: basename(command))
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-r, --priority PRIO Journal priority (emerg, alert, crit, err, warning, notice, info, debug)
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-l, --log LOGFILE Write stdout+stderr to LOGFILE instead of journald
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-d, --dir LOGDIR Directory for autogenerated log files (default: /tmp/$USER/runner)
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-p, --pidfile PATH Write daemon PID to PATH
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-u, --umask UMASK Set umask for the daemon (default: 0022)
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-h, --help Show this help and exit
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When no -l is provided, a log file is auto-generated:
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When no -l is provided and journald is available, output goes to journald.
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When -l is not provided and journald is not available, a logfile is auto-generated:
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<LOGDIR>/<command>.<YYYYMMDD-HHMMSS>.pid<$$>.log
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A pidfile is written as <logfile>.pid containing the child PID.
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EOF
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exit 1
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}
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@@ -56,20 +54,32 @@ EOF
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# Defaults
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logdir="/tmp/$USER/runner"
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logfile=""
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method="setsid"
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pidfile=""
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umask_val="0022"
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tag=""
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priority=""
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# Parse options until the `--` separator
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# Parse options up to --
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while [[ $# -gt 0 ]]; do
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case "$1" in
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-t|--tag)
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if [[ $# -lt 2 ]]; then echo "Missing argument for $1"; usage; fi
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tag="$2"; shift 2 ;;
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-r|--priority)
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if [[ $# -lt 2 ]]; then echo "Missing argument for $1"; usage; fi
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priority="$2"; shift 2 ;;
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-l|--log)
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if [[ $# -lt 2 ]]; then echo "Missing argument for $1"; usage; fi
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logfile="$2"; shift 2 ;;
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-d|--dir)
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if [[ $# -lt 2 ]]; then echo "Missing argument for $1"; usage; fi
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logdir="$2"; shift 2 ;;
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-m|--method)
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-p|--pidfile)
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if [[ $# -lt 2 ]]; then echo "Missing argument for $1"; usage; fi
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method="$2"; shift 2 ;;
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pidfile="$2"; shift 2 ;;
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-u|--umask)
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if [[ $# -lt 2 ]]; then echo "Missing argument for $1"; usage; fi
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umask_val="$2"; shift 2 ;;
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-h|--help)
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usage ;;
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--)
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@@ -81,130 +91,202 @@ while [[ $# -gt 0 ]]; do
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esac
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done
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# Remaining args are the command to run
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if [[ $# -eq 0 ]]; then
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echo "Error: no command specified."
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usage
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fi
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# Preserve the command and args
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# Build command array from remaining args.
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cmd=( "$@" )
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cmd_basename=$(basename "${cmd[0]}")
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timestamp=$(date +%Y%m%d-%H%M%S)
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mkdir -p -- "${logdir}"
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if [[ -z "${logfile}" ]]; then
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logfile="${logdir}/${cmd_basename}.${timestamp}.pid$$.log"
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# If tag not set, default to command basename
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if [[ -z "$tag" ]]; then
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tag="${cmd_basename}"
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fi
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pidfile="${logfile}.pid"
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# Detect systemd-cat
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systemd_cat_path=""
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if command -v systemd-cat >/dev/null 2>&1; then
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systemd_cat_path=$(command -v systemd-cat)
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fi
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# Validate method
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case "${method}" in
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setsid|nohup) ;;
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*)
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echo "Invalid method: ${method}. Allowed: setsid|nohup"
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exit 2
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;;
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esac
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# Prepare environment for child
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# We construct a small wrapper for safe daemonization:
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start_with_setsid() {
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# Prefer existing setsid binary (coreutils/util-linux)
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if ! command -v setsid >/dev/null 2>&1; then
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return 1
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fi
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# Use setsid to start the process in a new session. We:
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# - set a conservative umask
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# - change to / to avoid keeping directories busy
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# - close stdin and redirect stdout/stderr to logfile
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#
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# We run setsid directly with the command array so arguments are preserved.
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#
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# Note: redirecting >"$logfile" 2>&1 < /dev/null outside ensures the setsid child
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# inherits the redirections.
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(
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umask 022
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cd / || true
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# exec will replace the subshell with the command
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exec "${cmd[@]}"
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) >"${logfile}" 2>&1 < /dev/null &
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child_pid=$!
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# Detach the job from this shell's job table if possible
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disown "$child_pid" 2>/dev/null || true
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# setsid the already-forked child to start a new session. Some systems allow:
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# setsid -w <pid>
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# but that's nonportable; instead we try to re-exec the command under setsid.
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# If `setsid` can't be applied to the backgrounded PID, we respawn via setsid:
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if setsid true >/dev/null 2>&1; then
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# Respawn under setsid to ensure proper session leader if available.
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# Kill the previous child (it is still running) and restart under setsid.
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# To avoid races: only do this if cmd is still running and the pid we started is a shell wrapper.
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if kill -0 "$child_pid" 2>/dev/null; then
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# Attempt to terminate wrapper and spawn a true setsid child.
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kill "$child_pid" 2>/dev/null || true
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# Short sleep to allow process cleanup (best-effort)
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sleep 0.05
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fi
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# Now start the real setsid-backed child with same redirections
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setsid "${cmd[@]}" >"${logfile}" 2>&1 < /dev/null &
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child_pid=$!
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disown "$child_pid" 2>/dev/null || true
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fi
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printf '%s' "$child_pid"
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return 0
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}
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start_with_nohup() {
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# Use nohup as fallback; nohup will ignore HUP but doesn't start a new session.
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nohup "${cmd[@]}" >"${logfile}" 2>&1 < /dev/null &
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child_pid=$!
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disown "$child_pid" 2>/dev/null || true
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printf '%s' "$child_pid"
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return 0
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}
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# Main launcher: pick method and start
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echo "Launching command: ${cmd[*]}"
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echo "Log file: ${logfile}"
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echo "Method: ${method}"
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child_pid=""
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if [[ "${method}" == "setsid" ]]; then
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# Try to start via setsid; if setsid not present, fallback to nohup
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if child_pid=$(start_with_setsid); then
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: # success
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# If user provided logfile explicitly, force file mode
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use_journal=false
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if [[ -n "${logfile}" ]]; then
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use_journal=false
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else
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if [[ -n "${systemd_cat_path}" ]]; then
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use_journal=true
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else
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echo "setsid not available, falling back to nohup"
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child_pid=$(start_with_nohup)
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use_journal=false
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fi
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fi
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# Prepare logfile if needed
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mkdir -p -- "${logdir}"
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if ! $use_journal; then
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if [[ -z "${logfile}" ]]; then
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logfile="${logdir}/${cmd_basename}.${timestamp}.pid$$.log"
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fi
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# Ensure file exists and is writable
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: > "${logfile}" || { echo "Cannot write to log file: ${logfile}"; exit 1; }
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fi
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# Helper: quote command for printing
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quoted_cmd() {
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local i out=""
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for i in "$@"; do
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printf -v i "%q" "$i"
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out="${out} ${i}"
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done
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printf '%s' "${out# }"
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}
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# Build the inner script to run under setsid. We inject expanded variables from outer shell.
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if $use_journal; then
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# Compose systemd-cat args (escape tag and priority safely)
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# Note: we rely on simple token expansion; tag/priority are validated minimally below.
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journal_args=()
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journal_args+=( "-t" )
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journal_args+=( "$tag" )
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if [[ -n "$priority" ]]; then
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journal_args+=( "-p" )
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journal_args+=( "$priority" )
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fi
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# Validate priority loosely (allow common names or numeric)
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case "$priority" in
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""|emerg|alert|crit|err|warning|notice|info|debug|0|1|2|3|4|5|6|7) ;;
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*)
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echo "Warning: unknown priority '$priority' — journald may reject it." >&2 ;;
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esac
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# Prepare a single string of quoted journal args for insertion into the -c script
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# We need to protect values with single quotes if they contain special chars.
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journal_args_escaped=""
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for a in "${journal_args[@]}"; do
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# replace every single quote with '\'"\''
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a_escaped=${a//\'/\'"\'"\'}
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journal_args_escaped="$journal_args_escaped '$a_escaped'"
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done
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inner_script=$(cat <<'EOF'
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umask __UMASK__
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cd / || true
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# Close fds (best-effort)
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if [ -d /proc/self/fd ]; then
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for fdpath in /proc/self/fd/*; do
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fdnum=${fdpath##*/}
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case "$fdnum" in
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0|1|2) continue ;;
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esac
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eval "exec ${fdnum}>&-" 2>/dev/null || true
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done
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else
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maxfd=$(ulimit -n 2>/dev/null || echo 256)
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case "$maxfd" in (*[!0-9]*|"") maxfd=256 ;; esac
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fd=3
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while [ "$fd" -le "$maxfd" ]; do
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eval "exec ${fd}>&-" 2>/dev/null || true
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fd=$((fd+1))
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done
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fi
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# Redirect stdio: stdin -> /dev/null, stdout+stderr -> systemd-cat (journal)
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exec </dev/null
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# Note: the systemd-cat command and its args are inserted by the outer script.
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exec > >( __SYSTEMD_CAT__ ) 2>&1
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# Exec the target command; "$@" expands to the command and its args passed after --
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exec "$@"
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EOF
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)
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# Substitute placeholders with safe values
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inner_script=${inner_script//'__UMASK__'/"$umask_val"}
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# Build the systemd-cat invocation string (path + args) — shell-escaped
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# We need a single token string like: /bin/systemd-cat -t 'tag' -p 'priority'
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systemd_cat_cmd="$(printf '%s' "$systemd_cat_path")$journal_args_escaped"
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# Replace placeholder __SYSTEMD_CAT__ with the built command
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inner_script=${inner_script//'__SYSTEMD_CAT__'/"$systemd_cat_cmd"}
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# Start the detached process via setsid
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setsid bash -c "$inner_script" -- "${cmd[@]}" &
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else
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# Fallback: redirect to logfile (file mode)
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inner_script=$(cat <<'EOF'
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umask __UMASK__
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cd / || true
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# Close fds (best-effort)
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if [ -d /proc/self/fd ]; then
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for fdpath in /proc/self/fd/*; do
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fdnum=${fdpath##*/}
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case "$fdnum" in
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0|1|2) continue ;;
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esac
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eval "exec ${fdnum}>&-" 2>/dev/null || true
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done
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else
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maxfd=$(ulimit -n 2>/dev/null || echo 256)
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case "$maxfd" in (*[!0-9]*|"") maxfd=256 ;; esac
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fd=3
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while [ "$fd" -le "$maxfd" ]; do
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eval "exec ${fd}>&-" 2>/dev/null || true
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fd=$((fd+1))
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done
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fi
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exec </dev/null
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exec > "__LOGFILE__" 2>&1
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exec "$@"
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EOF
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)
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inner_script=${inner_script//'__UMASK__'/"$umask_val"}
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# Escape logfile path for safe insertion (single-quote style)
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log_escaped=${logfile//\'/\'"\'"\'}
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inner_script=${inner_script//'__LOGFILE__'/"'$log_escaped'"}
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setsid bash -c "$inner_script" -- "${cmd[@]}" &
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fi
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child_pid=$!
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# Try to disown if supported
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if command -v disown >/dev/null 2>&1; then
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disown "$child_pid" 2>/dev/null || true
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fi
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# Optionally write pidfile
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if [[ -n "${pidfile}" ]]; then
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mkdir -p -- "$(dirname "${pidfile}")"
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printf '%s\n' "${child_pid}" > "${pidfile}"
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fi
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echo "Started command: $(quoted_cmd "${cmd[@]}")"
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echo "Script PID: $$"
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echo "Daemon PID: ${child_pid}"
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if $use_journal; then
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echo "Output destination: systemd-journald (via $(printf '%s' "$systemd_cat_path"))"
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echo "Journal tag: ${tag}"
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if [[ -n "${priority}" ]]; then
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echo "Journal priority: ${priority}"
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fi
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else
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child_pid=$(start_with_nohup)
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echo "Log file: ${logfile}"
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fi
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# Write pidfile (best-effort)
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if [[ -n "${child_pid}" ]]; then
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printf '%s\n' "${child_pid}" > "${pidfile}" 2>/dev/null || true
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if [[ -n "${pidfile}" ]]; then
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echo "PID file: ${pidfile}"
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fi
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# Reporting
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echo "Script PID: $$"
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if [[ -n "${child_pid}" ]]; then
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echo "Child PID: ${child_pid}"
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else
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echo "Child PID: (unknown)"
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fi
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echo "Pidfile: ${pidfile}"
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echo "Started at: $(date --iso-8601=seconds 2>/dev/null || date +%Y-%m-%dT%H:%M:%S%z)"
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echo
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echo "To follow the log: tail -F ${logfile}"
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exit 0
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if ! $use_journal; then
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echo
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echo "To follow the log: tail -F ${logfile}"
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else
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echo
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echo "To view logs for this tag: journalctl -t ${tag} -f"
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fi
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Reference in New Issue
Block a user