copy paste code works but not as a script - bash

Question

I wrote a script with six if statements that looks like this:
#!/usr/bin/bash
if [ -n $var1 ]
then
for f in /path/*.fastq.gz
do
x=${f/%.fastq.gz/_sample1-forward.fastq.gz}
y=${f/%.fastq.gz/_sample1-forward.out}
q=${f/%.fastq.gz/_temp.fastq.gz}
command [options] -i $f -o $temp${x##*/}
cp $temp${x##*/} $temp${q##*/}
done
else
echo "no $var1"
for f in /path/*.fastq.gz
do
q=${f/%.fastq.gz/_temp.fastq.gz}
cp $f $temp${q##*/}
done
fi
The other five statements do a similar task for var2 to var6. When I run the script I get unexpected output (no errors no warnings), but when I copy paste each of the if statements to terminal I end up with the exact result I would expect. I've looked for hidden characters or syntax issues for hours now. Could this be a shell issue? Script written on OSX (default zsh) and execution on server (default bash). I have a feeling this issue is similar but I couldn't find an answer to my issue in the replies.
Any and all ideas are most welcome!
Niwatori

Answer 1

You should maybe look at the shebang. I think proper usage would be #!/usr/bin/env bash or #!/bin/bash.

Answer 2

thanks for the help, much appreciated. Shebang didn't seem to be the problem although thanks for pointing that out. Shellcheck.net reminded me to use
[[ ]]
for unquoted variables, but that didn't solve the problem either. Here's what went wrong and how I 'fixed' it:
for every variable the same command (tool) is used which relies on a support file (similar in format but different content). Originally, before every if statement I replaced the support file for the previous variable with the one needed for the current variable. For some reason (curious why, any thoughts are welcome) this didn't always happen correctly.
As a quick workaround I made six versions of the tool, all with a different support file and used PYTHONPATH=/path/to/version/:$PYTHONPATH before every if statement. Best practice would be to adapt the tool so it can use different support files or an option that deals with repetitive tasks but I don't have the time at the moment.
Have a nice day,
Niwatori