September 28

Utilities: CHMOD

Linux: CHMOD

Enter the permissions as needed for your files to find the numerical value to chmod your file.

Check the desired boxes or directly enter a valid
numeric number to see its value in other formats.


  Owner Group Other

Typical Chmod permissions values:

664 or -rw-r–r–   web pages and images viewed by surfers.
666 or -rw-rw-rw-  – log files or pages that are written to.
755 or -rwxr-xr-x  – perl scripts to make them executable.
755 or -rwxr-xr-x  – directories are usually given this value.
777 or -rwxrwxrwx  – for files that are written to by all.
777 or -rwxrwxrwx  – directories that have files created inside them.

What is Owner, Group and Other?

Owner – the user/owner of a file or directory.
Group – individuals who are in the same group.
Other – users that are not the owner or part of the group.

By using this calculator you agree that we are not liable for anything that may happen by your use.

More about chmod

Changes the permission of a file.


chmod [OPTION]… –reference=RFILE FILE…
-c, –changes like verbose but report only when a change is made
–no-preserve-root do not treat `/’ specially (the default)
–preserve-root fail to operate recursively on `/’
-f, –silent, –quiet suppress most error messages
-v, verbose output a diagnostic for every file processed
–reference=RFILE use RFILE’s mode instead of MODE values
-R, –recursive change files and directories recursively
–help display this help and exit
–version output version information and exit

u – User who owns the file.
g – Group that owns the file.
o – Other.
a – All.
r – Read the file.
w – Write or edit the file.
x – Execute or run the file as a program.

Numeric Permissions:
CHMOD can also to attributed by using Numeric Permissions:

400 read by owner
040 read by group
004 read by anybody (other)
200 write by owner
020 write by group
002 write by anybody
100 execute by owner
010 execute by group
001 execute by anybody


The above numeric permissions can be added to set a certain permission, for example, a common HTML file on a Unix server to be only viewed over the Internet would be:

chmod 644 file.htm

This gives the file read/write by the owner and only read by everyone else (-rw-r–r–).

Files such as scripts that need to be executed need more permissions. Below is another example of a common permission given to scripts.

chmod 755 file.cgi

This would be the following 400+040+004+200+100+010+001 = 755 where you are giving all the rights except the capability for anyone to write to the file.cgi file(-rwxr-xr-x).

chmod 666 file.txt

Finally, another common CHMOD permission is 666, as shown below, which is read and write by everyone.

Additional information

Below is an example of how a file may be listed when typing ( ls -l ) at the prompt as well as information on how to interpret it.

-rw-rw-r– 1   selene  123   Feb 03 15:36   file.txt

rw rw- r– 1 selene 123 Feb 03 15:36 file.txt
File owner group everyone else links owner size mod date file name

Related commands

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Posted September 28, 2011 by Timothy Conrad in category "Linux", "Utilities

About the Author

If I were to describe myself with one word it would be, creative. I am interested in almost everything which keeps me rather busy. Here you will find some of my technical musings. Securely email me using - PGP: 4CB8 91EB 0C0A A530 3BE9 6D76 B076 96F1 6135 0A1B