Unix Permissions

Every directory and file in a unix system has permissions indicating whether it can be accessed and by whom. The permissions can be seen by doing a long listing of the directory with

ls -l

The fields on the left indicate permission. Here are two examples.

drwxr-xr-x 2 joeuser  joegrp  512  May 26  14:19  subdir

The first example is a directory named "subdir". The first character, "d," tells you that it is a directory, not a file. The next nine characters represent the permissions, in groups of three. The first three refer to you, the User; the next three refer to your Group; and the last three refer to Others. In this example User has permission to (r)ead, (w)rite, and e(x)ecute (To execute a directory means you can change directory (cd) into it). Anyone in your group has permission to read and execute but not write and anyone else (other) has permission to read and execute.

-rw-r--r-- 1 joeuser  joegrp  2954 May 22  14:26  myfile.html

The second example shows a file. Now the first character is simply a "-". The user can read and write, and group and other can read only.

Files can have execute permission, too. This indicates that it is either a script (in perl or a shell language like csh or sh) or it is a compiled program originally written in Fortran, C, Pascal or something similar. If you have written a shell script that you want to execute just by typing its name, then turn on the execute permission. Compiled programs automatically get execute permission once they have compiled successfully.

Permissions can be changed with chmod.

If you are having trouble with a Web site, read up on Web Site Permissions.

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	Unix Permissions Every directory and file in a unix system has permissions indicating whether it can be accessed and by whom. The permissions can be seen by doing a long listing of the directory with `ls -l` The fields on the left indicate permission. Here are two examples. drwxr-xr-x 2 joeuser joegrp 512 May 26 14:19 subdir The first example is a directory named "subdir". The first character, "d," tells you that it is a directory, not a file. The next nine characters represent the permissions, in groups of three. The first three refer to you, the User; the next three refer to your Group; and the last three refer to Others. In this example User has permission to (r)ead, (w)rite, and e(x)ecute (To execute a directory means you can change directory (cd) into it). Anyone in your group has permission to read and execute but not write and anyone else (other) has permission to read and execute. -rw-r--r-- 1 joeuser joegrp 2954 May 22 14:26 myfile.html The second example shows a file. Now the first character is simply a "-". The user can read and write, and group and other can read only. Files can have execute permission, too. This indicates that it is either a script (in perl or a shell language like csh or sh) or it is a compiled program originally written in Fortran, C, Pascal or something similar. If you have written a shell script that you want to execute just by typing its name, then turn on the execute permission. Compiled programs automatically get execute permission once they have compiled successfully. Permissions can be changed with chmod. If you are having trouble with a Web site, read up on Web Site Permissions.
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