Command showing different behaviour when running from terminal and when Using as Shortcut

blueray Published at Dev

blueray

I am using KUbuntu 18.04.1

I am trying to extract text from screenshot using spectacle (Screenshot app of KUbuntu) & gocr (OCR tool)

If I give the commands one after another in Konsole (Terminal of KUbuntu)

First:

spectacle -r -b -n -o /home/UserName/Documents/Translate/input.jpg

Second:

gocr -i /home/UserName/Documents/Translate/input.jpg | xsel -b

It Works.

if I create a bash file screen_ts.sh and put the code

#!/bin/bash
# Dependencies: gocr xsel

# Take Screenshot and Save it to a File
spectacle -r -b -n -o /home/UserName/Documents/Translate/input.jpg

# Extract text from the saved file
gocr -i /home/UserName/Documents/Translate/input.jpg | xsel -b

exit

Open Konsole and type ./screen_ts.sh , it works

But, if I Make the file executable and double click, it take screenshot but does not save the text in clipboard.

Again if I create a custom shortcut using

Custom Shortcut > Trigger Alt + Q & Action /home/UserName/Documents/Translate/screen_ts.sh

it take screenshot but does not save the text in clipboard. Same behavior as double click.

What is going on here?

danzel

From man xsel:

By default, this program outputs the selection without modification if both standard input and standard output are terminals (ttys). Otherwise, the current selection is output if standard output is not a terminal (tty), and the selection is set from standard input if standard input is not a terminal (tty). If any input or output options are given then the program behaves only in the requested mode.

This is a bit misleading, but there is an interesting comment in the source code:

Checking stdin/stdout for being a tty is NOT reliable to tell what the user wants. This is because child processes inherit the file descriptors of their parents; an xsel called in a script that is e.g. daemonized (not attached to a tty), or called with a redirection or in a pipeline will have non-tty file descriptors on default. The redirection/piping issue also applies to "grouped" or "compound" commands in the shell (functions, subshells, curly-brace blocks, conditionals, loops, etc.). In all these cases, the user must set the mode of operation explicitly.

...and that's the solution: tell xsel explicitly to read from stdin by adding the -i option:

gocr -i /home/UserName/Documents/Translate/input.jpg | xsel -b -i

Collected from the Internet

Please contact [email protected] to delete if infringement.

edited at2021-03-5

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