How does touch command work internally in Linux?

The touch command in Linux is primarily used to create empty files or update the timestamps of existing files. When you use the command, it interacts with the filesystem to either create new file entries (if the specified file does not exist) or modify the metadata of existing files (if the file already exists).

Internally, the touch command performs the following steps:

1. Checks whether the specified file exists.
2. If the file exists, it updates its access and modification timestamps to the current time. This is done through system calls like utime or utimes.
3. If the file does not exist, it creates an empty file. This is accomplished using system calls like creat or open with the appropriate flags.

The command can also accept various options and arguments, such as specifying a different timestamp or creating multiple files at once.

Example of using the touch command: