difference between ' and "

[ArmenD]

for the life of me, I have seen a bizillion times ' and " used in command line and scripting.

Would someone plz in human terms explain what the difference is between ' and ". When do we use which?

thanks in advnace,

 

[chipperMDW]

Enclosing characters in single quotes (`'') preserves the literal value of each character within the quotes. A single quote may not occur between single quotes, even when preceded by a backslash.

Enclosing characters in double quotes (`"') preserves the literal value of all characters within the quotes, with the exception of `$', ``', and `\'. The characters `$' and ``' retain their special meaning within double quotes (*note Shell Expansions:. The backslash retains its special meaning only when followed by one of the following characters: `$', ``', `"', `\', or `newline'. Within double quotes, backslashes that are followed by one of these characters are removed. Backslashes preceding characters without a special meaning are left unmodified. A double quote may be quoted within double quotes by preceding it with a backslash.

The special parameters `*' and `@' have special meaning when in double quotes (*note Shell Parameter Expansion:.

In human terms, double quotes will allow you to include whitespace in a token, and will inhibit something like a shell glob, but still allows for parameter expansion (via $) and command substitution (via `) unless you backslash-quote those two characters.

Single quotes are more of an "absolute" quote. No expansion occurs whatsoever in single quotes.