function::switch_file - Linux


The switch_file command provides a convenient way to exchange file descriptors between running processes. It enables inter-process communication and sharing of files across different processes.


switch_file [options] destination-fd source-fd file


  • -a: Automatically lock the destination file for exclusive access.
  • -b: Reserve space in the destination file to accommodate the incoming file.
  • -c: Close the destination file after the operation.
  • -f: Force the creation of the destination file.
  • -l: Lock the destination file for shared access.
  • -n: Do not create the destination file if it does not exist.
  • -t: Move the file instead of creating a copy.


Example 1: Creating a Channel Between Two Processes

cat file1 | switch_file - 3 2

This command creates a channel from stdin (read from file1) to stdout (write to fd 3).

Example 2: Swapping File Descriptors

switch_file -t 3 4 file3.txt

This command swaps the file descriptors for stdin (fd 3) and file file3.txt (fd 4).

Common Issues

  • Destination File Does Not Exist: When using -n, the command will fail if the destination file does not exist. Use -f to force creation.
  • Permissions Denied: Ensure that the user running the command has write permissions to the destination file.


switch_file can be integrated with other commands such as:

  • cat: Create a pipe between processes using stdin and stdout.
  • tee: Send output to multiple destinations.
  • tail: Monitor changes in the destination file.

Related Commands

  • dup2(): Duplicate a file descriptor.
  • fcntl(): Perform file control operations.
  • /proc/self/fd: List file descriptors for the current process.