Getting unary operator error on Shell script Linux [duplicate]

Question

I get this error:

getengine.sh: line 38: [: =: unary operator expected
getengine.sh: line 41: [: =: unary operator expected

Here is the script:

if [ $1 = "m" ]; then #this is line 38
    initial=`curl -s http://some/2016/30-publish`
    label=`curl -s http://test/${initial}.l/artifacts/info.xml`
elif [ $1 = "s" ]; then # this is line 41
    initial=`curl -s http://some/2016/30-publish`
    label=`curl -s http://test/${initial}.l/artifacts/info.xml`
fi

I don't understand what is wrong? This works perfectly locally but when I run it in a linux environment server I get this error...any help would be appreciated

...btw, what do you expect your code to do when neither m nor s is passed? — Charles Duffy
– Charles Duffy, Commented Oct 25, 2016 at 15:26
I have an else to print out usage, btw the link you posted has no accepted answer: stackoverflow.com/questions/22179405/… — arabian_albert
– arabian_albert, Commented Oct 25, 2016 at 15:42

Charles Duffy · Accepted Answer · 2016-10-25 15:24:44Z

3

You need more quotes.

# this is correct
[ "$1" = "m" ]

...not...

# WRONG: this becomes [ = m ] if $1 is empty, producing your error.
[ $1 = "m" ]

answered Oct 25, 2016 at 15:24

Charles Duffy

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7 Comments

arabian_albert Over a year ago

You sure, why is this working locally for me?

arabian_albert Over a year ago

I'm running locally with a mac

Charles Duffy Over a year ago

@arabian_albert, yes, I'm sure. The reason it's working locally for you is that you aren't testing with $1 being empty, whereas it's empty when it runs on the server.

Charles Duffy Over a year ago

@arabian_albert, ...though you could also be masking the problem by using a non-POSIX-compliant shell such as zsh for your local testing, which doesn't follow POSIX-mandated rules regarding string-splitting of unquoted expansions.

Charles Duffy Over a year ago

Just because it's hardcoded doesn't mean it can't be emptied later. A bad set command could do that, f'rinstance, or a shift. Use bash -x yourscript to see what's actually happening in practice during execution.

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