Unix Permissions Calculator
Build chmod numeric and symbolic permissions from read/write/execute flags for user, group and others.
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User
Group
Other
Result
Numeric:
Symbolic:
About Unix Permissions Calculator
This Unix permissions calculator converts read, write and execute selections into chmod numeric and symbolic permission values.
It is useful for server setup, deployment work and shell troubleshooting when you need to confirm the right permission combination before running `chmod`.
Permission Values Reference
| Octal | Symbolic | Read | Write | Execute |
|---|---|---|---|---|
| 7 | rwx | Yes | Yes | Yes |
| 6 | rw- | Yes | Yes | No |
| 5 | r-x | Yes | No | Yes |
| 4 | r-- | Yes | No | No |
| 3 | -wx | No | Yes | Yes |
| 2 | -w- | No | Yes | No |
| 1 | --x | No | No | Yes |
| 0 | --- | No | No | No |
Frequently Asked Questions
- What does chmod 755 mean?
- 755 means owner has rwx (4+2+1=7), group has r-x (4+0+1=5), others have r-x (4+0+1=5). This is common for executable scripts where everyone can read and execute.
- What does chmod 644 mean?
- 644 means owner has rw- (4+2+0=6), group has r-- (4+0+0=4), others have r-- (4+0+0=4). This is standard for readable files that only the owner can modify.
- Why use symbolic vs numeric permissions?
- Numeric (755) is concise for full permission sets. Symbolic (u+rwx,g+rx,o+rx) is clearer for modifying specific bits without affecting others.
- What is the sticky bit?
- The sticky bit (1000) on directories prevents users from deleting files they don't own. Commonly set on /tmp as 1777.
- What do setuid and setgid bits do?
- Setuid (4000) runs executables with owner permissions. Setgid (2000) runs with group permissions or inherits group on directories.
- What is the umask value?
- Umask subtracts from default permissions. A umask of 022 results in 755 for directories and 644 for files.