How to set file permissions with touch command

Question

It seems that whenever I create a file with touch the permissions are set to: -rw-r--r--.

Is there some way that I can configure the permissions with touch or does this have to be done after with a different command?

Answer 1

You can modify your umask to allow (for most implementations) more read/write privileges, but not executable, since generally the requested permissions are 0666.

If your umask is 022, you'll see touch make a 0644 file.

Interestingly, POSIX describes this behavior in terms of creat:

1. If file does not exist:

   The creat() function is called with the following arguments:

   • The file operand is used as the path argument.

   • The value of the bitwise-inclusive OR of S_IRUSR, S_IWUSR, S_IRGRP, S_IWGRP, S_IROTH, and S_IWOTH is used as the mode argument.

and it is only by following the links to creat, then to open, noticing the mention of umask and back-tracking to open (and creat) to verify that umask is supposed to affect touch.

For umask to affect only the touch command, use a subshell:

(umask 066; touch private-file)
(umask 0; touch world-writable-file)
touch file-as-per-current-umask

(note that in any case, if the file existed beforehand, touch will not change its permissions, just update its timestamps).

Answer 2

You can manipulate the umask. Generally it's set to 022 which means when a user creates a file, it will get permission of 0644, you can manipulate umask according to your needs.