Linux command for managing file permissions.

Linux command for managing file permissions.

• A. ls
• B. chmod
• C. chown
• D. cat

Answer: (B)

Managing file permissions means controlling who can read, write, or execute a file for the owner, the owner’s group, and others. The tool used to change those permission bits is chmod. It’s the command you run when you want to grant or restrict access, whereas listing permissions is done with ls. Chown, by contrast, changes who owns the file, and cat simply displays the file’s contents, which is unrelated to changing permissions. Using chmod, you can set exact permissions in two common ways. In numeric (octal) form, chmod 755 script.sh gives the owner full rights (read, write, execute) and gives group and others read and execute only. chmod 644 file.txt assigns read and write for the owner, and read-only for group and others. In symbolic form, you can add or remove specific rights, such as chmod u+x script.sh to grant the owner execute permission, or chmod go-w file.txt to remove write permission from group and others. If you don’t own the file or don’t have appropriate privileges, chmod won’t allow changes. The key idea is that chmod is the standard tool to set and modify permission bits, which is precisely what “managing file permissions” refers to.

Managing file permissions means controlling who can read, write, or execute a file for the owner, the owner’s group, and others. The tool used to change those permission bits is chmod. It’s the command you run when you want to grant or restrict access, whereas listing permissions is done with ls. Chown, by contrast, changes who owns the file, and cat simply displays the file’s contents, which is unrelated to changing permissions.

Using chmod, you can set exact permissions in two common ways. In numeric (octal) form, chmod 755 script.sh gives the owner full rights (read, write, execute) and gives group and others read and execute only. chmod 644 file.txt assigns read and write for the owner, and read-only for group and others. In symbolic form, you can add or remove specific rights, such as chmod u+x script.sh to grant the owner execute permission, or chmod go-w file.txt to remove write permission from group and others.

If you don’t own the file or don’t have appropriate privileges, chmod won’t allow changes. The key idea is that chmod is the standard tool to set and modify permission bits, which is precisely what “managing file permissions” refers to.