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Found this error to be quite weird because previously my script was working and but after I moved it from the server I was working on to my local machine, it stopped working and just gave me an 'unexpected operator' error.
# Else if the script is being run in the arrayscripts directory, add /output/ ... elif [ $basePath == "arrayscripts" ]; then echo "$dscr has started to run." cpuPath="`pwd`/output/cpu.binary" txtPath="`pwd`/output/cpu.txt" csvPath="`pwd`/output/cpu.csv"
If your actual shell is /bin/sh [contrary to the initial question, but as discussion commentary has made clear], use = rather than == in your test expression:
elif [ "$basePath" = arrayscripts ]
Note that the right-hand side doesn't need to be quoted in this case, since it contains no expansions and no syntactically-sensitive characters.
Alternately, if this issue is reproducible when using bash, the obvious problem is missing quotes.
Use either
[ "$basePath" = arrayscripts ] # this is POSIX compatible
or
[[ $basePath = arrayscripts ]] # this works only with bash
Otherwise, the number of arguments $basePath expands into is undefined -- it may expand into zero arguments, making the statement
[ = arrayscripts ]
...which would try to use = as a unary operator, which it isn't...
or if $basePath contained, say, "true -o bar =", it could expand into something like
[ true -o bar = arrayscripts ]
...resulting in program behavior very different from what you actually want.
Bottom line: When writing for shells which follow POSIX rules (basically, anything but zsh or fish), quote your expansions unless you have a specific and compelling reason to do otherwise. (Use of the bash/ksh extension [[ ]] provides such a reason, by introducing a context in which string-splitting of expansion results and glob expansion don't take place).
This is an error you'd get if you were executing the script with a POSIX shell like dash. dash is the default /bin/sh on some platforms such as Ubuntu and Debian.
== is specific to bash ( Bashism ) and is not compatible with POSIX shells like dash, which uses only = to test string equality.
== and = are treated as the same operator in bash, so either can be used.
I managed to get my script working by changing the comparison function from '==' to '=' as suggested by 'alister' in the unix and linux forums ( http://www.unix.com/shell-programming-and-scripting/141856-how-avoid-unexpected-operator-error-when-comparing-2-strings.html ) and so my script looked like this
# Else if the script is being run in the arrayscripts directory, add /output/ ... elif [ "$basePath" = "arrayscripts" ]; then echo "$dscr has started to run." cpuPath="`pwd`/output/cpu.binary" txtPath="`pwd`/output/cpu.txt" csvPath="`pwd`/output/cpu.csv"
Hope that if anyone gets this same error as I did, that this answer will help them. .
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