Linux chmod Command
Permissions explained properly: what the three digits mean, symbolic versus numeric mode, and why 777 is almost never the right answer.
Formula
chmod [OPTION]... MODE FILE...
How to use it
- The synopsis at the top shows the general form of the command.
- Click any example to copy it straight to your clipboard.
- The options table lists only the flags worth remembering — run man for the exhaustive list.
Examples
| chmod 644 file.txt | owner can edit, everyone else can read |
| chmod 755 script.sh | everyone can run it, only the owner can edit |
| chmod +x script.sh | make it executable, keeping other bits |
Questions people ask
What does 755 actually mean?
Owner gets 7 — read, write and execute. Group and others get 5 — read and execute, but not write. It is the standard mode for directories and scripts.
Why do directories need the execute bit?
On a directory, execute means the right to enter it and access what is inside. A directory with read but not execute lets you list the names and nothing more.
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Last updated 22 August 2026