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I believe this line 

if test "$suman_inspect" -eq "yes"; then

is causing this error (verbatim):

bash: test: no: integer expression expected

I formulated the above test expression because I saw this example online:

 if test "$#" -eq "0"; then

where this test checks to see if the length of the arguments array is 0.

So is there something wrong with both these checks? I am not sure I understand how the first could be valid but the second one invalid.

Alexander Mills
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  • Both test expressions in the question are invalid - to compare strings you need to use the `==` operator, not the `-eq` operator – Alexander Mills Nov 10 '17 at 01:04

1 Answers1

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Note that -eq is for integer comparisons. For string comparisons, use == (or =). Thus, you should use the following:

if test "$suman_inspect" == "yes"; then
    # do something
fi

The same distinction applies for inequality operators (-gt, -lt, -ge, -le, and -ne being used for numerical comparisons, and >, <, >=, <=, and != being used for string comparisons).

Note that you can also use [ expression ] in place of test expression; the two are synonymous.

user001
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  • yeah it's a shame the `-eq` operator cannot compare two strings, as long as both arguments are already strings, oh well. – Alexander Mills Nov 10 '17 at 00:54
  • @Alexander Mills: I have long thought that `eq`, being a string, should be used for string comparisons, while `=`, being a mathematical symbol, should be used for numerical comparisons, but alas it's not the case. – user001 Nov 10 '17 at 00:57
  • no language is perfect lol – Alexander Mills Nov 10 '17 at 01:03
  • @AlexanderMills String and integer comparisons are different, so it's important to have different symbols for them. For instance, `[ 05 -eq 5 ]` is true, but `[ 05 = 5 ]` is not -- they're different strings that represent the same integer. Also, `[ 5 -lt 11 ]` is true, but `[ 5 '<' 11 ]` is not, because 5 is less than 11 numerically, but comes after it "alphabetically" (i.e. in sorting order). BTW, `=` is preferred over `==` with `test` and `[ ]`, for compatibility reasons. – Gordon Davisson Nov 10 '17 at 03:06