Trying to make a program where it takes two arguments from the command line and adds them together. However if there are not two arguments passed it needs to ask for two arguments.
if [$# = 2]; then
ans=$(($1 + $2))
echo "$1 + $2 = $ans"
else
echo "Pass me two Arguments!"
fi
What is the correct way to check whether the number of arguments is equivalent to a number?
You got it but just forgot some escaping quotes and the spaces before/after the test ([$# = 2]). Fixed:
if [ "$#" = 2 ]; then
ans=$(($1 + $2))
echo "$1 + $2 = $ans"
else
echo "Pass me two Arguments!"
fi
Odd as it may seem, [ is actually the name of an executable just like echo, ls and what have you:
$ which [
/usr/bin/[
This means that if you don't have a space after [, you're trying to start a program called [your_statement. The space is needed to separate the executable from its arguments.
Most *nix systems allow you to use the equivalent test executable rather than [ for a more intuitive syntax: if test "$#" = 2; then ...
By omitting the quotes in the if statement, bash/shell interprets everything following the # as a comment and so does SO's code formatting tool (everything after if [$ is greyed out in your code but not in mine because I added the double quotes in "$#").
Btw. ShellCheck can be very helpful.
