将带有单引号和双引号的参数传递给Shell脚本

Question

We are trying to pass an argument with single and double quotes to a shell script and executing with this argument. In echo its printing correctly but for the command we are getting as "Unterminated quoted value"

Please see the script and argument passing method:

[root@geopc]/root# ./myscript.sh 'localhost:9199/jmxrmi -O java.lang:type=GarbageCollector,name="PS MarkSweep" -A CollectionCount -K duration'


#!/bin/bash
out=`/usr/lib64/nagios/plugins/check_jmx -U service:jmx:rmi:///jndi/rmi://$1`
echo $1
echo $out

After executing we are getting output as

$1 : localhost:9199/jmxrmi -O java.lang:type=GarbageCollector,name="PS MarkSweep" -A CollectionCount -K duration

$out : JMX CRITICAL Unterminated quoted value

In Shell Script we we hard code value of $1 and then executing we are getting correct result.

We tried passing of arguments as follows:

./myscript.sh 'localhost:9199/jmxrmi -O java.lang:type=GarbageCollector,name=\"PS MarkSweep\" -A CollectionCount -K duration'

in this case error is : JMX CRITICAL Invalid character '"' in value part of property

./myscript.sh 'localhost:9199/jmxrmi -O java.lang:type=GarbageCollector,name="\"PS MarkSweep\"" -A CollectionCount -K duration'

in this case error is JMX CRITICAL Unterminated quoted value

So anyone please help me on it.

Answer 1

The problem is that you're expecting quotes and escapes in variables to be interpreted the same as quotes in your script.

In Java terms, this is the same as expecting:

String input="\"foo\", \"bar\"";
String[] parameters = { input };

to be the same as this:

String[] parameters = { "foo", "bar" };

The real solution in both language is to let the input be an array of elements:

#!/bin/bash
out=`/usr/lib64/nagios/plugins/check_jmx -U service:jmx:rmi:///jndi/rmi://"$1" "${@:2}"`
echo "$1"
echo "$out"

and then running:

./myscript.sh localhost:9199/jmxrmi -O java.lang:type=GarbageCollector,name="PS MarkSweep" -A CollectionCount -K duration

HOWEVER!!

This requires discipline and understanding.

You'll notice that this is not a drop-in solution: the script is now being called with multiple parameters. This is a very strict requirement. If this script is being called by another program, that program also has to be aware of this. It needs to be handled end-to-end.

If you store this in a config file for example, it'll be YOUR responsibility to serialize the string in such a way that YOU can deserialized into a list. You can't just hope that it'll work out, because it won't. Unlike Java, there will be no compiler warning when you confuse strings and lists.

If this is not something you want to get involved with, you can instead use eval . This is a bad practice because of security and robustness issues, but sometimes it's Good Enough:

yourcommand="/usr/lib64/nagios/plugins/check_jmx -U service:jmx:rmi:///jndi/rmi://$1"
echo "$yourcommand"  # Make sure this writes the right command
eval "$yourcommand"  # This will execute it as if you copy-pasted it