Inside a bash script STDOUT to LOG, STDERR to LOG and console

Question

I have a bash script and want to write

• STDOUT to a log file only (not to the console)
• STDERR to the same log file and to the console

I tried

#!/bin/bash

main() {
        echo "HELLO"
        >&2 echo "ERROR"
}

LOGFILE=/tmp/mylog.log
main 1>>$LOGFILE 2>(tee -a $LOGFILE)

HELLO goes to the log file and ERROR just goes to the console.

What am I doing wrong?

Answer 1

You may use this script:

#!/usr/bin/env bash

logfile='/tmp/mylog.log'

# open fd=3 redirecting to 1 (stdout)
exec 3>&1

# redirect stdout/stderr to a file but show stderr on terminal
exec >"$logfile" 2> >(tee >(cat >&3))

#exec 1>"$logfile" 2> >(tee -a "$logfile") 

main() {
   echo "HELLO"
   echo "ERROR" >&2
}

main

# close fd=3
exec 3>&-

It will write ERROR on your terminal but both HELLO and ERROR to $logfile.