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POWhat is the correct usage of (nested | double | simple) quotes
 

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  1. POWhat is the correct usage of (nested | double | simple) quotes
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    <p>I'm sure this question may seem foolish to some of you, but I'm here to learn.<br> Are these assumptions true for most of the languages ?<br> <strong>EDIT</strong> : OK, let's assume I'm talking about Perl/Bash scripting. </p> <pre><code>'Single quotes' </code></pre> <p>=> No interpretation at all (e.g. '$' or any metacharacter will be considered as a character and will be printed on screen)</p> <pre><code>"Double quotes" </code></pre> <p>=> Variable interpretation</p> <p>To be more precise about my concerns, I'm writing some shell scripts (in which quotes can sometimes be a big hassle), and wrote this line :</p> <pre><code>CODIR=`pwd | sed -e "s/$MODNAME//"` </code></pre> <p>If I had used single quotes in my sed, my pattern would have been '$MODNAME', right ? (and not the actual value of $MODNAME, which is `alpha' in this particular case)</p> <p>Another problem I had, with an awk inside an echo :</p> <pre><code>USAGE=`echo -ne "\ Usage : ./\`basename $0\` [-hnvV]\n\ \`ls -l ${MODPATH}/reference/ | awk -F " " '$8 ~ /\w+/{print "&gt; ",$8}'\`"` </code></pre> <p>I spent some time debugging that one. I came to the conclusion that backticks were escaped so that the interpreter doesn't "split" the command (and stop right before «basename»). In the awk commmand, '$8' is successfully interpreted by awk, thus not by shell. What if I wanted to use a shell variable ? Would I write awk -F "\"$MY_SHELL_VAR\"" ? Because $MY_SHELL_VAR as is, will be interpreted by awk, won't it ?</p> <p>Don't hesitate to add any information about quoting or backticks !</p> <p>Thank you ! :)</p>
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    1. COI retagged with shell-scripting, since that's what you appear to be basing your question on. In short, every programming/scripting language treats the various quotes in their own way.
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      1. USaberrant80
 

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