How do I write an error message in BASH for a specific input?

Question

I am new to BASH, well scripting in general, and am writing a BASH script but no idea what to do

I have a script working currently, where with specifics user inputs, it writes a file for a subsequent software to work.

However, specific numbers and phrases are needed for the software to work, so I want to write an error message, that if the input isn't correct, instead of the script failing and starting from scratch, an error message is shown and you have a redo

##Writing inp.add Files##
printf "\n${bold}Writing inp.add file\n${normal}"
read -p "Number of Processors: " NPROC
read -p "Wavefunction File (with .wfx): " WFX
read -p "Coord file (CUBE or .txt): " COORD
echo "AOM_MAT OCCUP automatically picked"
read -p "Overlap (LO or LDO): " OVERLAP
printf "\nRunning Gaussian: ${bold}$JOBNAME \n${normal}"

Matthieu · Answer 1 · 2019-06-15T18:50:39.943

0

Use while cond ; do ... done:

while true ; do
    read -p "Input var: " var
    [[ -n "$var" ]] && break
    echo "Please enter a non-empty value"
done
echo "You entered $var"

Will ask for input until it's non-empty.

edited Jun 15 '19 at 18:50

answered Jun 15 '19 at 18:11

Matthieu

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Thats not exactly what i meant. for example in the part of the code: read -p "Overlap (LO or LDO): " OVERLAP the only options for the software is LO and LDO, so if one of the 2 arent entered, then an error message is needed and repeat that question – Thomas Bates Jun 15 '19 at 18:15
@ThomasBates you should edit your question with that remark, it makes it *a lot* different, and probably not a duplicate anymore. – Matthieu Jun 15 '19 at 18:20
well i can't find the question that i apparently duplicated so the flag doesnt help me – Thomas Bates Jun 15 '19 at 18:24
1

@ThomasBates The four duplicates are linked at the top of the question. – Benjamin W. Jun 15 '19 at 18:29
my apologies, I am new to this website – Thomas Bates Jun 15 '19 at 18:32
1

FYI you don't need [[ 1 == 1 ]] you can just use [[ 1 ]] – Mike Q Jun 15 '19 at 18:33
@MikeQ thanks, I thought so but couldn't test it easily here... – Matthieu Jun 15 '19 at 18:38
1

Actually you don't need `[[` either. The idiomatic endless loop is `while true` or even `while :` – tripleee Jun 15 '19 at 18:46
@tripleee now that you say it, I remember using that a few years ago! – Matthieu Jun 15 '19 at 18:51

How do I write an error message in BASH for a specific input?

1 Answers1