Differences between revisions 2 and 3
Revision 2 as of 2007-05-09 18:20:43
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Editor: GreyCat
Comment:
Revision 3 as of 2007-09-13 19:19:33
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Editor: BetterWorld
Comment: Add example for non-obvious backslashing behaviour
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 * Backslashes (\) inside backticks are handled in a non-obvious manner. ''(Example desired!)'' Inside {{{$()}}}, there are no such surprises.  * Backslashes (\) inside backticks are handled in a non-obvious manner:

  {{{
  echo "`echo \\a`" # prints a
  echo "`echo \\\a`" # prints \a
  echo "`echo \\\\a`" # prints \a}}}

Inside {{{$()}}}, there are no such surprises.

Anchor(faq82)

Why is $(...) preferred over `...` (backticks)?

For several reasons:

  • It makes nesting command substitutions easier. Compare:
    •   x=$(grep $(dirname "$path") file)
        x=`grep \`dirname "$path"\` file`
    It just gets uglier and uglier after two levels.
  • It's easier to read.
  • Newbies who see $() don't normally press the wrong keys. On the other hand, newbies who see `cmd` often mangle it into 'cmd' because they don't know what a backtick is.

  • Backslashes (\) inside backticks are handled in a non-obvious manner:
    •   echo "`echo \\a`"      # prints a
        echo "`echo \\\a`"     # prints \a
        echo "`echo \\\\a`"    # prints \a

Inside $(), there are no such surprises.

The only time backticks are preferred is when writing code for the oldest Bourne shells, which do not know about $().

BashFAQ/082 (last edited 2021-07-18 10:40:15 by geirha)