Comparing Strings in Arrays in Bash Scripting

Question

Alright, this is a really simple little thing but it's gotten to the point where I've exhausted 2-3 hours trying to find out why this isn't working and have gotten nowhere.

I'm trying to make Bash/Shell-Script program, and at one point in it, I want to check the contents of an array of strings to see if the string is blank. My code is as follows:

#Display any words the user corrected, and what he/she corrected it with (ignore blank corrections)
printf "\n\n" "MISPELLED  /  CORRECTIONS"
for (( i=0; i<${#words[*]}; i++)); do
if [!"${corrections[$i]}"=""]; then    //this is line 25
   printf "\n ${words[$i]}   ${corrections[$i]}"
fi
done

I'm not positive if the way I used the ! operator was legal, but with or without it, I get the run-time error:

./test: line 25: [=]: command not found

I can post the rest of the code if need be, though I'm mostly confident that the "corrections" array is properly filled with strings.

You need to put spaces between [ and the rest of the things in the if. — Tom Fenech
– Tom Fenech, Commented Oct 7, 2014 at 23:08
Gah! I could have sworn I had tried that at least once before! Well that's all it was, thank you! — aredscout
– aredscout, Commented Oct 7, 2014 at 23:14
It is better to use -z for checking if empty or -n for non-empty. if [ -z "${corrections[$i]}" ] will be true if string is empty (blank). if [ -n "${connections[$i]}" ] will be true if string is not empty (not blank). — alvits
– alvits, Commented Oct 7, 2014 at 23:17
if your array elements doesn't contains spaces, e.g. each element is one word, you can remove empty elements with arr2=( ${arr1[@]} ) — clt60
– clt60, Commented Oct 7, 2014 at 23:44

Tom Fenech · Accepted Answer · 2014-10-07 23:21:44Z

1

In the shell, [ is a command, so it is important to leave spaces before and after it. On top of that, if you want to check that a string is not empty, you can use -n:

if [ -n "${corrections[$i]}" ]

answered Oct 7, 2014 at 23:21

Tom Fenech

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