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31 lines
1.2 KiB
Plaintext
31 lines
1.2 KiB
Plaintext
---
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syntax: markdown
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tags: [tldr, linux]
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source: https://github.com/tldr-pages/tldr.git
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---
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# flock
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> Manage file locks from shell scripts.
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> It can be used to ensure that only one instance of a command is running.
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> More information: <https://manned.org/flock>.
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- Run a command with a file lock as soon as the lock is available:
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`flock {{path/to/lock.lock}} {{command}}`
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- Run a command with a file lock, or exit if the lock is currently being held (with exit code 1):
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`flock {{path/to/lock.lock}} {{[-n|--nonblock]}} {{command}}`
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- Run a command with a file lock, or exit with a specific error code if the lock is currently being held:
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`flock {{path/to/lock.lock}} {{[-n|--nonblock]}} {{[-E|--conflict-exit-code]}} {{123}} {{command}}`
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- Run a command with a file lock, waiting up to 10 seconds for the lock to be available before giving up:
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`flock {{path/to/lock.lock}} {{[-w|--timeout]}} 10 {{command}}`
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- Backup a bunch of files, waiting for the previous `tar` command to finish if it's still running elsewhere and holding the same lock file (can be used in a `cron` job that runs often):
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`flock {{path/to/backup.lock}} {{tar -cvf path/to/backup.tar path/to/data/}}`
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