Ubuntu – How to redirect output to screen as well as a file

bashredirect

My aim is to log all output from a script into a directory that the script is going to create.

For example, I have:

~/.abc.sh:

#! /bin/bash
rails new myapp

When I run…

cd ~/code
. ~/.abc.sh

…that will create a new Rails app in directory ~/code/myapp.

When Rails is creating an app, it outputs a whole lot of text that I want to capture and store in a log file in the same directory the rails command newly created. I also want to display that text in the terminal as well.

How do I go about doing this?

Best Answer

You can use the tee command for that:

command | tee /path/to/logfile

The equivelent without writing to the shell would be:

command > /path/to/logfile

If you want to append (>>) and show the output in the shell, use the -a option:

command | tee -a /path/to/logfile

Please note that the pipe will catch stdout only, errors to stderr are not processed by the pipe with tee. If you want to log errors (from stderr), use:

command 2>&1 | tee /path/to/logfile

This means: run command and redirect the stderr stream (2) to stdout (1). That will be passed to the pipe with the tee application.

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