How to redirect output to a file and stdout

linux bash file-io io stdout
SCdF picture SCdF · Jan 7, 2009 · Viewed 692.9k times · Source

In bash, calling foo would display any output from that command on the stdout.

Calling foo > output would redirect any output from that command to the file specified (in this case 'output').

Is there a way to redirect output to a file and have it display on stdout?

Answer

Zoredache picture Zoredache · Jan 7, 2009

The command you want is named tee:

foo | tee output.file

For example, if you only care about stdout:

ls -a | tee output.file

If you want to include stderr, do:

program [arguments...] 2>&1 | tee outfile

2>&1 redirects channel 2 (stderr/standard error) into channel 1 (stdout/standard output), such that both is written as stdout. It is also directed to the given output file as of the tee command.

Furthermore, if you want to append to the log file, use tee -a as:

program [arguments...] 2>&1 | tee -a outfile

Related questions

Split files using tar, gz, zip, or bzip2

I need to compress a large file of about 17-20 GB. I need to split it into several files of around 1GB per file. I searched for a solution via Google and found ways using split and cat commands. But …

Read More
Shell/Bash shortcut for bulk renaming of files in a folder

Is there a shortcut in Shell/Bash that can rename all the files in a folder based on a regex or some other criteria. What I am looking for here is in my folder documents, that has let's say a 100 …

Read More
pass stdout as file name for command line util?

I'm working with a command line utility that requires passing the name of a file to write output to, e.g. foo -o output.txt The only thing it writes to stdout is a message that indicates that it ran …

Read More