How do I suppress GtkDialog warnings in zenity and yad using Bash redirection in a script?

I'm trying to suppress GtkDialog warnings in zenity and yad:

$ zenity --error --text hello
Gtk-Message: GtkDialog mapped without a transient parent. This is discouraged.

Error redirection and filtering works:

$ zenity --error --text hello 2> >(grep -v GtkDialog >&2)

YEAH... Annoying warning message disappears!!

This can be placed in ~/.bashrc for development work as answered here:

• How to make zenity “transient parent” warning disappear permanently (using function)

and here:

• How to make zenity “transient parent” warning disappear permanently (using alias)

When creating a script for others to use though, you don't want the burden of them changing their ~/.bashrc.

I'm having trouble creating a typing shortcut for: 2> >(grep -v GtkDialog >&2) to be used inside script.

For many reasons variable assignment GTK_SPAM="2> >(grep -v GtkDialog >&2)" followed later by variable usage "$GTK_SPAM" doesn't work.

alias zenity="zenity 2> >(grep -v GtkDialog >&2)" before calling script works but, I can't use this within a script.

Using an array to hold the typing shortcut isn't working:

$ aGtkSpam=(2\> \>\(grep -v GtkDialog \>\&2\))

$ DumpArray "${aGtkSpam[@]}"
Array Elements:
0: 2>
1: >(grep
2: -v
3: GtkDialog
4: >&2)

$ zenity --error --text hello "${aGtkSpam[@]}"
This option is not available. Please see --help for all possible usages.

$ yad --text hello 2> >(grep -v GtkDialog >&2)

$ yad --text hello "${aGtkSpam[@]}"
Gtk-Message: GtkDialog mapped without a transient parent. This is discouraged.

I found many excellent generic answers on word-splitting and parameters which should solve my problem but a specific syntax eludes me.

Any clues?

Solution 1:

I don't think syntax alone can help you here - because of the order in which the shell sets up redirections and expands variables. To give a very simple illustration:

$ arr=( ">" "/dev/null" )
$ set -x
$ echo foo "${arr[@]}"
+ echo foo '>' /dev/null
foo > /dev/null

i.e. everything has been expanded "correctly", but > /dev/null has simply become a list of string arguments passed to echo.

You could force evaluation using eval:

$ eval echo foo "${arr[@]}"
+ eval echo foo '>' /dev/null
++ echo foo

but really it would be better to redirect the stream for the duration of your script using exec:

exec 2> >(grep -v GtkDialog >&2)

or, if you want to be able to turn the filter off before the end of the script, then based on After using exec 1>file, how can I stop this redirection of the STDOUT to file and restore the normal operation of STDOUT? it should be possible to do

exec 3>&2 2> >(grep -v GtkDialog >&2)

and then later

exec 2>&3 3>&-

to recover the duplicated stream.

Solution 2:

You can define and use aliases in your script if you set the expand_aliases shell option, e.g.:

#!/bin/bash
shopt -s expand_aliases
alias zenity='zenity 2> >(grep -v GtkDialog >&2)'
…

Now every zenity line behaves as if 2> >(grep -v GtkDialog >&2) were added and you can disable this behaviour as usual by prepending a backslash or command:

\zenity        # and
command zenity

both ignore the alias.

Further reading

• Why doesn't my Bash script recognize aliases?

Solution 3:

You can use function in the script. zenity and yad have useful info in stdout, so I suggest to redirect just stderr to /dev/null

#/bin/bash

zen_nospam() {
  zenity "$@" 2&>1 >(grep -v GtkDialog >&2)
}

zen_nospam --error --text hello

btw function can be defined in .bashrc if needed in command line, not script