Ok, this is probably going to be ultra obvious to anyone that has spent more time with bash than I have.
I'm trying to run this code:
#!/bin/bash
if ["1" -eq "2"]
then
echo "True"
else
echo "False"
fi
but when I execute the file, it sends back
./test.sh: line 3: 1: command not found
False
There must be something major I'm missing. I've seen people use a semicolon after the brackets, this doesn't seem to make any difference... :S
You need to add a space after the [ and before the ] like so:
if [ "1" -eq "2" ]
However, that way is deprecated and the better method to use is:
#!/bin/bash
if ((1 == 2))
then
echo "True"
else
echo "False"
fi
[ or (( )) ?(( )) is used for arithmetic evaluation which is exactly what the OP wants to do.yep eq is used only for arithmetic comparaisons.
for string comparison you have to use =
#!/bin/bash
if [ "1" = "2" ]
then
echo "True"
else
echo "False"
fi
plus you need some space around the brackets.
[ 10 -gt 2 ] is true. Comparisons, on the other hand, can be for strings or numbers. One example, you've shown. Others that are specific to shells that support [[: string: [[ "10" > "2" ]] (false) or [[ "10" -gt "2" ]] (true). Again, it's not the quotes that make the difference.
[ not be syntax, but instead be a regular command (as far as the parser is concerned; there's actually a built-in implementation so /bin/[ and /usr/bin/[ aren't used by common shells, but that's just a performance optimization). It's completely normal to need a space between the name of a command and its arguments.Try adding spaces around your brackets:
if [ "1" -eq "2" ]
which [and you'll see. And you can't execute a program with arguments written without a whitespace... (And as others have answered, -eq is for integers only. Which it will tell you when using [ correct)[. The reason is that[is a command -- it's an alias fortest. These days it's a shell builtin but you can find/bin/[on most systems.