Shell Tips 2: Quote Unquote

February 14, 2011

There are three different kinds of quote: single quotes, double quote, and backticks. Single quotes


are true quotes and suspend all special characters except ‘ itself.

Double quote
"" suspend execution and filename expansion, but shell variables are still expanded.
Illustrating filename expansion:


will put a list of files in the variable $MyList, whereas


will store an asterisk character in it.
If you just want to quote a common-or-garden string, always use single quotes.
Are double quotes useful? Very! If you double-quote all your variables (except
on the left of an assignment)…


you can avoid a lot of problems.
Double quotes are useful in combination with backticks or or $() operator. The point of this gizmo is to take the
output of a command and turn it into a string. If a command produces output on multiple line, the
formatting gets lost. For instance


will store a list of files all in one line:

echo $OutPut1


aFile anotherFile



will maintain the formatting:

echo "$OutPut2"




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