1

In my program, I want to get substrings of the inputs to compare them and save them as variables however my script seems to be freezing/stuck in a loop.

#!/bin/bash

ram="5G";
file="forge.jar"
dir="MC/Eternal/"

echo $@

for var in $@
do
    begin= `awk -v awkvar="$var" '{print substr($awkvar,1,2)}'`
    end= `awk -v awkvar="$var" '{print substr($awkvar,3)}'`
    echo $begin $end
    if [ $begin = "-r" ]
    then
        echo Setting ram to $end
        ram=$end
    elif [ $begin = "-d" ]
    then
        echo "Looking for directory MC/$out"
        directory=$end
    elif [ $begin = "-f" ]
    then
        echo "Looking for file $out"
        file=$end
    fi
done
echo running command: java -Xms1G -Xmx$ram -jar $dir$file
echo Do you want to run it? [Y/n]:
read input
if [ input = "y" ]
    java -Xms1G -Xmx$ram -jar $dir$file
else
    echo cancelled
fi

When I input ./runserver.sh -r10G -dfoo -fmc.jar I expect to get java -Xms1G -Xmx10G -jar MC/foo/mc.jar ... but the program seems to get stuck on the begin= ... line. I've tried begin = awk '{print substr($awkvar,1,2)} and just begin = awk '{substr($awkvar,1,2)}' with the backticks around the awk statement. I am new to Linux and I have just successfully launched and connected to my Minecraft server. Any and all help is appreciated.

Edit: Found that if I use the "${var:x:y}" instead of the awk function I can get a substring. However, it seems that the program is trying to run the arguments instead of making it a string by the error it gives me ./runserver.sh: line 11: -r: command not found

2 Answers 2

1

You are not allowed any blanks on shell assignments to variables. So begin= ``awk... is just initialising begin to empty and then trying to run the output of awk as a command. Same for end=

The two awks are getting stuck because you have not given them any input from files or stdin. Maybe you meant to just do that in a BEGIN rule, not from real data.

Presumably you intend to use awk just to get a couple of chars out of $var. There are shell options that will do substrings very nicely -- no need to run awk for that.

The awks won't work because you are using the shell construct for $awkvar. You should not use the $ inside awk itself (it designates a field number inside awk).

You have discovered the shell substring operator, but you don't show your updated script.

The new fail in if [ $begin = "-r" ] is because it expands $begin, and the test sees [ -r = -r ] and thinks -r is an option. If you use the better version of the test syntax and quote it, it will work.

paul $ begin="-r"
paul $ if [[ "${begin}" = "-r" ]]; then echo true; fi
true
paul $ 
-1

Your code for parsing command line arguments is way too complex. Use the "getopts" bash builtin instead. See https://stackoverflow.com/questions/16483119/an-example-of-how-to-use-getopts-in-bash for examples.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.