False positive grep?

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# 8  
Old 04-19-2020
&2>/dev/null is still odd, the & is too many. The & before a descriptor number is needed on the RHS only, to distinguish it from a file name.
And, the only errors that a [[ ]] can produce are "syntax error", "not an integer", "division by zero". You want to see them!
If you want to supress an error from an embedded sub shell expression than redirect it within the sub shell.

In general, only suppress error messages when it makes sense - they help you!

And yes, I meant the
builtin echo "$NUM" | $GREP -E -q "[a-zA-Z]"  && continue

that should become
[[ "$NUM" =~ [a-zA-Z] ]] && continue

Last edited by MadeInGermany; 04-19-2020 at 09:24 AM.. Reason: correction: no surrounding *
This User Gave Thanks to MadeInGermany For This Post:
# 9  
Old 04-19-2020
Thank you, I'll try to keep that present (2 & null) after reviewing current code.
What is this RHS you are refering to please?

Uhm, not really on the possible error topic - as I experienced it differently.
Phew... i still had that in the terminal so I could scroll to it...

# | 45) swarm.util.mkdir                                                                     46) swarm.util.which | #
# | > ^[[A/home/sea/prjs/SWARM/data/libs/util.enduser: Zeile 538: [[: [: Syntax Fehler: Operator erwartet. (Fehlerverursachendes Zeichen ist \"[\").
/home/sea/prjs/SWARM/data/libs/util.enduser: Zeile 561: [: [: Ganzzahliger Ausdruck erwartet.
/home/sea/prjs/SWARM/data/libs/util.enduser: Zeile 568: [: Syntax Fehler: Operator erwartet. (Fehlerverursachendes Zeichen ist \"[\").
/home/sea/prjs/SWARM/data/libs/util.enduser: Zeile 536: [[: [: Syntax Fehler: Operator erwartet. (Fehlerverursachendes Zeichen ist \"[\").

False positive grep?-swarm20-falsegrepjpg

This is with code of the 'initial' post/s ; where the 'catch' was different from the code we're talking about now (recent post with code).
This 'symbol' cannot be compared to a number, thus creating an 'expected' error message, which I wanted to get rid of -> as it breaks the visual experience.

Could you advice a better handling for this situation?
-> Catching arrow keys without showing the enduser an error message? <-
# 10  
Old 04-19-2020
Why do I keep forgetting to post the other half?

Even with the suggested change by Ravinder, I keep getting these error messages.
# | 45) swarm.util.mkdir                                                                     46) swarm.util.which | #
# | > ^[[A++ [[ [ =~ ^\[\[ ]]                                                                                    | #
++ set +x
/home/sea/prjs/SWARM/data/libs/util.enduser: Zeile 540: [[: [: Syntax Fehler: Operator erwartet. (Fehlerverursachendes Zeichen ist \"[\").
/home/sea/prjs/SWARM/data/libs/util.enduser: Zeile 538: [[: [: Syntax Fehler: Operator erwartet. (Fehlerverursachendes Zeichen ist \"[\").
/home/sea/prjs/SWARM/data/libs/util.enduser: Zeile 563: [: [: Ganzzahliger Ausdruck erwartet.
/home/sea/prjs/SWARM/data/libs/util.enduser: Zeile 570: [: Syntax Fehler: Operator erwartet. (Fehlerverursachendes Zeichen ist \"[\").

Where I would have expected a continue before the ++set +x...

My point beeing, sadly, that even with the suggest speed-increase changes, it fails with an error message to the user.

And you were right... (I know wasnt what you wanted to point out):
if [[ ${#NUM} -ge 0 ]] >/dev/null

Is what now solves my expections.

I really wish that those checks would have work/ed out as expected/anticpated, but none did, nor does.
So, I'm left with what is working (gives the expected result), allthough not nice.

Nevermind.. I tested wrong (forgot to actualy press an arrow key on the X'th 'last' run)...
It's still all messed up when pressing an arrow key.... Smilie

Last edited by sea; 04-19-2020 at 09:08 AM..
# 11  
Old 04-19-2020
That explains it; and your photo shows a non-ascii character.
It's not sufficient to sort out [a-zA-Z].

With an ERE you can ensure the input is a number:
[[ $NUM =~ ^[0-9]+$ ]] || continue
echo "$NUM is a positive integer"

[[ $NUM =~ ^-?[0-9]+$ ]] || continue
echo "$NUM is an integer"

RHS == right hand side
This User Gave Thanks to MadeInGermany For This Post:
# 12  
Old 04-19-2020
Thank you very much!
This works perfectly! Smilie
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