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flock — preventing a second run

cheat sheet · Ubuntu 24.04 · util-linux 2.39 https://lab.dimsanych.ru/en/wiki/flock/

Cheat sheet

flock -n /run/lock/clean.lock clean.sh busy — exit with code 1
flock -w 30 /run/lock/clean.lock clean.sh wait up to 30 seconds
flock /run/lock/clean.lock clean.sh wait as long as it takes
flock -n -E 75 /run/lock/clean.lock cmd busy — code 75
flock -n -o /run/lock/app.lock cmd children get no lock
lslocks -o COMMAND,PID,TYPE,PATH who holds which locks

Options

The main options are in the table below. The full list is in man flock.