linux - within - How to redirect output to a file and stdout

shell script redirect output to file (6)

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?

< command > |& tee filename # this will create a file "filename" with command status as a content, If a file already exists it will remove existed content and writes the command status.

< command > | tee >> filename # this will append status to the file but it doesn't print the command status on standard_output (screen).

I want to print something by using "echo" on screen and append that echoed data to a file

echo "hi there, Have to print this on screen and append to a file" 

Another way that works for me is,

<command> |& tee  <outputFile>

as shown in gnu bash manual


ls |& tee files.txt

If ‘|&’ is used, command1’s standard error, in addition to its standard output, is connected to command2’s standard input through the pipe; it is shorthand for 2>&1 |. This implicit redirection of the standard error to the standard output is performed after any redirections specified by the command.

For more information, refer redirection

Something to add ...

The package unbuffer has support issues with some packages under fedora and redhat unix releases.

Setting aside the troubles

Following worked for me

bash 2>&1 | tee output.log

Thank you ScDF & matthew your inputs saved me lot of time..

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

tee is perfect for this, but this will also do the job

ls -lr / > output | cat output

using tail -f output should work.