How to do a logical OR operation in Shell Scripting?

Question

I am trying to do a simple condition check, but it doesn't seem to work. If `$#` is equal to `0` or is greater than `1` then say hello. I have tried the following syntax with no success: if [ "$#" == 0 -o "$#" > 1 ] ; then echo "hello" fi if [ "$#" == 0 ] || [ "$#" > 1 ] ; then echo "hello" fi

Answer 1

To perform a logical OR operation in shell scripting, you can use the double vertical bar (||) operator. Here's how you can modify your code to use this operator:

if [ "$#" -eq 0 ] || [ "$#" -gt 1 ]; then

 echo "hello"

fi

In this code, the -eq and -gt operators are used to compare the number of arguments ($#) to the values 0 and 1, respectively. The || operator is used to combine the two conditions into a logical OR operation.

Note that the -o operator can also be used for a logical OR operation, but it is considered deprecated and may not work in all versions of the shell. Therefore, it is recommended to use || instead.

Also, make sure to use the correct comparison operators -gt and -eq for comparing integers, and not the greater-than (>) operator used for string comparison.