Bash use of zenity with console redirection

Question

In efforts to create more manageable scripts that write their own output to only one location themselves (via 'exec > file'), is there a better solution than below for combining stdout redirection + zenity (which in this use relies on piped stdout)?

parent.sh:

#!/bin/bash
    
exec >> /var/log/parent.out
    
( true; sh child.sh ) | zenity --progress --pulsate --auto-close --text='Executing child.sh')
[[ "$?" != "0" ]] && exit 1

...

child.sh:

#!/bin/bash

exec >> /var/log/child.out

echo 'Now doing child.sh things..'
...

When doing something like-

sh child.sh | zenity --progress --pulsate --auto-close --text='Executing child.sh'

zenity never receives stdout from child.sh since it is being redirected from within child.sh. Even though it seems to be a bit of a hack, is using a subshell containing a 'true' + execution of child.sh acceptable? Or is there a better way to manage stdout?

I get that 'tee' is acceptable to use in this scenario, though I would rather not have to write out child.sh's logfile location each time I want to execute child.sh.

Answer 1

Your redirection exec > stdout.txt will lead to error.

$ exec > stdout.txt
$ echo hello
$ cat stdout.txt
cat: stdout.txt: input file is output file

You need an intermediary file descriptor.

$ exec 3> stdout.txt
$ echo hello >&3
$ cat stdout.txt
hello