Loop through file to count field number

Question

I have a script bash to add users from a .txt file. It is really simple:

name firstname uid gid

space separated values

I want to check

Answer 1

On UNIX you'll return 0 in case of success and !=0 in case of an error. For me it makes more sense to return 0 when all records have 4 fields and 1 when not all records have 4 fields.

To achieve that, use exit:

awk 'NF!=4{exit 1}' file

FYI: awk will exit with 0 by default.

If you want to use it in a shell conditional:

#!/bin/bash
if ! awk 'NF!=4{exit 1}' file ; then
    echo "file is invalid"
fi

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PS: -F' ' in your example is superfluous because ' ' is the default field delimiter.