getopts flag parsing

POSIX option parsing with arguments; -n takes a value, -v is a switch

while getopts "n:v" o; do case $o in n) ns=$OPTARG;; v) verbose=1;; esac; done
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bash12 commands
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More bash commands

  • Bound command with timeout and kill
    timeout -k 5s 30s ./long_task.sh || echo "timed out: $?"

    SIGTERM at 30s then SIGKILL after 5s grace; exit 124 means it was killed

  • Dedicated fd for structured logging
    exec 3>>audit.log; echo "$(date -Is) start" >&3; exec 3>&-

    Open fd 3 to a file, write to it independently of stdout, then close it

  • zsh recursive glob and batch rename
    setopt extendedglob; print -l **/*(.); autoload zmv; zmv '(*).txt' '$1.bak'

    zsh: list only regular files recursively, then mass-rename safely with zmv

  • Strict mode with safe IFS
    set -euo pipefail; IFS=$'\n\t'

    Fail fast on errors, unset vars, pipe failures; split only on newline/tab

  • Cleanup temp dir via trap
    tmp=$(mktemp -d); trap 'rm -rf "$tmp"' EXIT INT TERM

    Auto-remove mktemp dir on exit/signal; note: quote $tmp to survive spaces

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