42 lines
1.2 KiB
Markdown
42 lines
1.2 KiB
Markdown
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---
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tags: [permissions, Linux]
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created: Friday, April 11, 2025
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---
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# chmod
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Modify file permissions.
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We can use symbols or numbers.
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For example:
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```sh
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chmod +x filename
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```
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To make a file executable.
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When we use numbers this is called an _absolute_ change, because all permission
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bits are being set at once in octal notation.
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Best just to memorise the most common sequences. Bear in mind that some only
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apply to files, rather than directories or executable programs.
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| Mode | Meaning | Applied to |
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| ---- | --------------------------------- | --------------------- |
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| 644 | user: r/w, group/other: r | files |
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| 600 | user: r/w, group/other: none | files |
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| 755 | user: r/w/e, group/other: r/e | directories, programs |
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| 700 | user: r/w/e, group/other: none | directories, programs |
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| 711 | user: r/w/e, group/other: execute | directories |
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### Useful options
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`-v` → verbose: tell the user what `chmod` is doing
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`-r` → work recursively, i.e apply the action to directories as well as files
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> You can list the contents of a directory if it's readable but you can only
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> access a file in a directory if the directory is executable!
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