gizmobench

Chmod Calculator

Convert a Unix permission mode by entering octal digits, pasting an ls-style permission string, or toggling owner, group and other permissions. See each class’s value and the special bits together, then copy the equivalent mode or example command.

Type an octal mode or an ls-style permission string, or choose bits below. Valid edits update both representations immediately.

Owner
7
Read 4 + write 2 + execute 1
Group
5
Read 4 + write 2 + execute 1
Others
5
Read 4 + write 2 + execute 1
Special bits

Leading octal digit: 0 = setuid 4 + setgid 2 + sticky 1

0755
rwxr-xr-x
chmod 0755 './path/to/file'
Example only. The quoted placeholder path is not a real target. Nothing is executed.

Read the bits

Files and directoriesFor files, r means read content, w means modify content and x means execute. For directories, r means list names, w means modify directory entries and x means search/traverse. Operations may require combinations of permissions.

Lowercase s/t versus uppercase S/TA lowercase s or t means the special bit and that class’s execute bit are both set. Uppercase S or T means the special bit is set while execute is off. These replace the x position, not r or w.

Set user ID and set group IDOn supported executable files these can affect the effective user or group identity. Setgid on directories commonly makes new entries inherit the directory’s group. Exact behavior depends on the operating system, file type and mount settings.

Sticky bitOn directories, the sticky bit restricts removal or renaming of entries, generally to the entry owner, directory owner or a privileged user. It does not independently grant read, write or search access.

Mode bits are one part of access controlACLs, privileges, mount options and other system rules can change effective access. The optional leading file-type character is accepted for conversion but is not a permission bit. Symbolic operations like u+x need an existing mode and are outside this listing converter.

Explains entered bits; does not execute commands or recommend access policies. Conversion runs locally. Inputs are not stored.

Common questions

What does chmod 755 mean?
0755 encodes owner read, write and execute (4 + 2 + 1 = 7), group read and execute (4 + 1 = 5), and others read and execute (5). Its symbolic string is rwxr-xr-x. The leading zero means no special bits are set. This describes the mode, not whether it is appropriate for a particular file.
Why are there three or four octal digits?
The last three digits describe owner, group and others. An optional leading digit encodes setuid (4), setgid (2) and sticky (1). This tool always displays all four digits so those bits are visible. Octal digits can only be 0 through 7.
What do s, S, t and T mean?
s or S in the owner execute position means setuid; in the group execute position it means setgid. t or T in the others execute position means sticky. Lowercase means the execute bit is also enabled; uppercase means execute is disabled. For example, 1777 is rwxrwxrwt and 7000 is --S--S--T.
Can I paste a complete ls -l line?
Paste just the nine permission characters, or the ten-character type-and-permission field such as drwxr-xr-x. Full filenames, dates, ACL markers and symbolic operations such as u+x are not accepted. The file-type character is ignored when calculating the permission mode.
Do these bits show all effective access?
No. Access can also depend on ACLs, privileges, mount options and operating-system rules. Files and directories interpret some bits differently: directory execute means search or traverse, while directory write concerns directory entries. Special-bit behavior also depends on the system and file type.
Does this run chmod or change any files?
No. It only converts entered bits in your browser. The example command uses a fixed, quoted placeholder path. Inputs are not saved or sent for conversion, and the tool does not recommend an access policy.

Explains entered bits; does not execute commands or recommend access policies.