cap_size - Linux


cap_size is a powerful utility used to calculate the size of the capability mask for a given process, user, or file. It provides detailed information about the capabilities held by these entities, enabling users to assess security risks and enforce proper access controls.


cap_size [options] <object>

where <object> can be one of the following:

  • process/pid: A running process specified by its process ID.
  • user/name: A user account specified by its username.
  • file: A file or directory specified by its path.


| Flag | Description |
| -p | Print the capability size for a process by its PID. |
| -u | Print the capability size for a user by their username. |
| -f | Print the capability size for a file or directory. |
| -v | Verbose mode, providing detailed information about each capability. |
| -h | Display help and usage information. |



cap_size -p 1234

This command prints the capability size for the process with PID 1234.


cap_size -u root

This command prints the capability size for the user with the username "root".


cap_size -f /etc/passwd

This command prints the capability size for the file "/etc/passwd".

Common Issues

Insufficient Permissions: If the user running cap_size does not have sufficient permissions to access the specified object, the command will return an error.

Non-Existent Object: If the specified object (process, user, or file) does not exist, cap_size will report an error.

Wrong Format: Ensure that the specified object is in the correct format (PID for process, username for user, path for file).


cap_size can be used in conjunction with other commands to facilitate security analysis and system administration tasks. For instance, it can be piped into commands like grep or awk to filter and analyze the output.


cap_size -p | grep cap_sys_admin

This command lists all processes with the cap_sys_admin capability.

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