bash Cookbook

Sending Both Output and Error Messages to Different Files

Problem

You are expecting output from a program but you don’t want it to get littered with error messages. You’d like to save your error messages, but it’s harder to find them mixed among the expected output.

Solution

Redirect output and error messages to different files.

$ myprogram 1> messages.out 2> message.err

Or more commonly:

$ myprogram > messages.out 2> message.err

Discussion

This example shows two different output files that will be created by the shell. The first, messages.out, will get all the output from the hypothetical myprogram redirected into it. Any error messages from myprogram will be redirected into message.err.

In the constructs 1> and 2> the number is the file descriptor, so 1 is STDOUT and 2 is STDERR. When no number is specified, STDOUT is assumed.

See Also

• Saving Output to Other Files

• Throwing Output Away