I'm writing a script to run a given program on a simulator while changing the argument supplied and I'm having a problem where bash keeps inserting single ticks around the double quotes that causes the simulator to crash spectacularly. How can I stop this from happening?


#./matrix_sim MM1.x86 1024 X86 gem5.opt


./gem5/build/$ARCHI/$TARGET gem5/configs/example/se.py -c ./$PROGRAM -o \"$ARGUMENT\"

When I run this script, what actually is output is

./gem5/build/X86/gem5.opt gem5/configs/example/se.py -c ./MM1.x86 -o '"2"'

But what I really want to happen is this

./gem5/build/X86/gem5.opt gem5/configs/example/se.py -c ./MM1.x86 -o "2"

How do I get rid of the single ticks on output?

closed as unclear what you're asking by Michael Homer, G-Man, Archemar, Kusalananda, don_crissti Sep 23 '17 at 11:28

Please clarify your specific problem or add additional details to highlight exactly what you need. As it's currently written, it’s hard to tell exactly what you're asking. See the How to Ask page for help clarifying this question. If this question can be reworded to fit the rules in the help center, please edit the question.

  • Do you want the program to actually get "2" as the option, or is 2 the right thing to pass? If the latter, just use "$ARGUMENT". – Kusalananda Feb 6 '17 at 17:44
  • Does the script need to hang around? If not, use exec ./gem5/... to make it replace itself with that final command. – thrig Feb 6 '17 at 17:59
  • You mean, in the debug output of bash -x? – Stéphane Chazelas Sep 22 '17 at 17:32
  • While the question is unclear, somehow google still finds it, someone who understands this should edit it, and not just bash -x, but also set -x in the script causes this behavior – tjb Oct 11 '18 at 9:13

Bash does not add single quotes to your string. The single quotes are how it makes the output of the set -x trace visually unambiguous. In bash, set -x produces visually unambiguous output by putting single quotes around strings that contain shell special characters (whitespace and !"#$&\()*;<>?[\]^`{|}~). Here, you're tracing a command which takes a parameter containing a ", so bash prints it out with single quotes around it to make it clear that the " is a literal character in the string and not something in the shell source syntax.

It seems that you didn't want to have a double quote in the argument. So don't put one.

You do need double quotes around variable expansions, but that's double quotes, in the shell syntax, not putting a quoted double quote so that a double quote character ends up in the string.

"./gem5/build/$ARCHI/$TARGET" gem5/configs/example/se.py -c "./$PROGRAM" -o "$ARGUMENT"

Just use "$ARGUMENT":

./gem5/build/$ARCHI/$TARGET gem5/configs/example/se.py -c ./$PROGRAM -o "$ARGUMENT"

Bash will add single quotes (in e.g. the set -x tracing output) when you use \"$ARGUMENT\" because you're making the double quotes part of the argument's value (this is most likely not what you want).


Unable to replicate:

$ ./in.sh program arg arch target
./gem5/build/arch/target gem5/configs/example/se.py -c ./program -o "arg"
$ cat in.sh
#./matrix_sim MM1.x86 1024 X86 gem5.opt


echo ./gem5/build/$ARCHI/$TARGET gem5/configs/example/se.py -c ./$PROGRAM -o \"$ARGUMENT\"

I've tried many manipulations to try to replicate what you're seeing and am unable to do so.

You could perhaps try:


and then removing the escaped quotes around your invocation:

echo ./gem5/build/$ARCHI/$TARGET gem5/configs/example/se.py -c ./$PROGRAM -o "$ARGUMENT"
  • I'm supposing he's looking at trace output from set -x. – Kusalananda Feb 6 '17 at 17:50

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