Shell Programming and Scripting

Thanks Johnsoe,
Your advice is good to know.

Note that this problem could also have been fixed by quoting the variables:

Code:

if [ "$var1" -gt 1500 -o "$var2" -gt 1000 -o "$var3" -gt 1000 -o "$var4" -gt 1000 -o "$var5" -gt 1000 ]

The unset variables in this case would evaluate as zero when performing the numeric comparisons used in this test command instead of giving a syntax error.

Don Cragun, I see quoting the variables is not helping:-

Code:

# cat test.sh
#!/bin/bash

var1=100
var3=1500

if [ "$var1" -gt 1500 -o "$var2" -gt 1000 -o "$var3" -gt 1000 ]
then
    echo "Success"
else
    echo "Failed"
fi

Code:

# ./test.sh
./test.sh: line 6: [: : integer expression expected
Failed

Code:

# uname
Linux GNU/Linux
# echo $SHELL
/bin/bash

Sorry, I should have said it wasn't a portable fix.

It works with ksh on OS X, but comparing an empty string using a numeric test operator is not required to work. However, I believe that even though it didn't give you what you wanted with bash on Linux, the diagnostic message would be easier to interpret. (At least I think it would be easier to try to find out what to look for when test says it expected an integer expression than it was to figure out what was wrong when it said too many arguments and meant that an unset variable caused a test operator to be misinterpreted as an operand.)

Of course the underlying problem of using variables that don't contain data of the type expected when they are expanded can only be fixed by verifying the format of data before it is used. And, we weren't shown the first 49 lines of the script that failed to set or verify that the variables used in this test contained numeric string values.