On Fri, Nov 25, 2011 at 1:46 PM, Scott <amorphous.yet....@gmail.com> wrote: > First, I read from various sources that backticks (`command`) are basically deprecated, with $(command) the preferred option (I may be a little loose with this definition). man ksh even alludes to this: > > <snip> ``' introduces an old-style command substitution <snip> > > Is there ANY differnece between the behavior of these, or is it just that the newer style is preferred for readability?
A later paragraph in the "Substitution" section describes differences in parsing. The classical example is then seen here: echo '\$x' echo `echo '\$x'` echo $(echo '\$x') The first and third both output \$x but the second outputs $x I.e., you can whip up a command that creates the output you desire, and then wrap it in $(...) without having to go through it adding backslashes like you do with backquotes. > Second, again in man ksh, I read: > > Note that $(< foo) has the same effect as $(cat foo), but it is carried out more efficiently because no process is started. > > When googling for similar examples, I always see the 'cat foo' example used. So is this form simply a shorthand for 'cat somefile', and not any other command (for example an awk or sed command)? Yes. Philip Guenther
