fchownat - Linux

Overview

fchownat is a command-line utility for changing the ownership of a file or directory. It works by specifying the file descriptor, which allows you to operate on files that are open or locked by other processes. This is useful in scenarios where traditional chown or chgrp commands may fail.

Syntax

fchownat(int dirfd, const char *path, uid_t owner, gid_t group, int flags)

Options/Flags

• -h, –help: Display usage information and exit
• -v, –verbose: Enable verbose output. Displays details of the files being modified.
• -f, –force: Suppress error messages if the owner or group cannot be changed.

Examples

# Change the owner of an open file:
fchownat(3, "file.txt", 1000, -1, 0)

# Change the group of a directory:
fchownat(-1, "dir", -1, 100, 0)

# Change both owner and group, using verbose output:
fchownat(-1, "file.txt", 1000, 100, AT_SYMLINK_NOFOLLOW | AT_REMOVEDIR) -v

Common Issues

• Ensure that you have sufficient permissions to change the ownership of the file or directory.
• The file descriptor provided must be valid and refer to an open file or directory.
• Using the -f flag may result in errors being silently ignored.

Integration

fchownat can be used in combination with other Linux commands to perform complex file management tasks. For example:

# Change the ownership of all files in a directory and its subdirectories:
find /dir -type f | while read file; do fchownat(-1, file, 1000, 100, 0); done

Related Commands

• chown: Change the ownership of files or directories.
• chgrp: Change the group ownership of files or directories.
• stat: Print file or directory information.