What is crw rw rw

Can someone please explain what the c special flag means? It's a character device based file Within Linux devices such as hardware are characterised in two ways:.

Character Devices c which are devices which transfer data in characters also known as bytes or bits such as mice, speaker etc. If you're running a decent Linux distro, that information plus more than you could probably ever need can be obtained with the command:.

It is 'character oriented device' is this case b means block oriented device Sign up to join this community. The best answers are voted up and rise to the top.

Stack Overflow for Teams — Collaborate and share knowledge with a private group. Create a free Team What is Teams? Learn more. Learn how to change these permissions using the chmod command.

Find out how default permissions for new files are configured via a user's umask value. File permissions define which user or system accounts have permissions to read, write, and execute specific files. There are also three other components when it comes to file mode bits, namely the setuid bit, the setgid bit, and the sticky bit.

As you'll see later, these "special mode bits" can only be used for certain files. File permissions are identified through file mode bits. These bits represent what actions can be carried out by specific user accounts. For example, if you run the command ls -l to list the files in the current directory, you'll see something similar to this at the beginning of each line in the results:. The repeated rwx sequences represent the notion of read r , write w , and execute x permissions for user , group , and other in that order.

Hence the -rwxrwxrwx above indicates that user, group, and other have read, write and execute permissions for that file or in other words: the owner of the file, anyone in the file's group, and everybody else has read, write, and execute permissions for that file. Note that the leading - you'll see in permissions like -rwxrwxrwx simply indicates that this is a normal file file type regular. Note that the d above indicates that the permissions are for a directory i.

This directory is readable, writeable, and executable by "user" whilst only readable and executable by "group" and "other". The above permissions show that the owner of this regular file has read and write permission but nobody else has any permissions for that file. You'll know it refers to a "character device" such as a tty where the "user" has read and write permission, the "group" has write permission, and "other" has no permissions.

To recap, the meanings of r , w , and x for each of the three categories "user", "group", and "other" are illustrated in the image below which shows an ls -l command run in a directory which contains filename. The user name shown in the image above is the name of the user account which owns the file normally the creator, but this can be changed using chown whilst the group name is the creator's primary group this can be changed using chgrp.

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