Re: $(grep anycommand anyfile) fail

[Dave B]

BlackEnvil wrote:

> Description: using ` ` or $() with command that use dirnames with spaces
> fail.
> 
> there are diferent dirnames with this problem, and different situations that
> cause these errors, not only with ls and not only with grep.
> 
> bye
> 
> 
> Repeat-By:
> 
> [blackenvil@space_star ~]$ cd $HOME; mkdir hello\ -world/; touch test; echo
> "ls hello\ -world/" > test; $(grep ls test);
> ls: invalid line width: orld/
> [blackenvil@space_star ~]$

There are actually two problems here.
After the command substitution, the shell does word splitting, and the
command it sees is this (spaced for readability):

ls   hello\   -world
     ^^^^^^   ^^^^^^
      arg1      arg2

The -world part is interpreted as the option -w to ls, and "orld" as the
argument to that option, which is an invalid line width. To fix that, use --
to mark the end of options. But even if you do that, you would still get an
error because ls would see two filenames: "hello\" and "-world", neither of
which exists.

> [blackenvil@space_star ~]$ cd $HOME; mkdir hello-\ world/; touch test; echo
> "ls hello-\ world/" > test; $(grep ls test);
> ls: cannot access hello-\: No such file or directory
> world/:
> [blackenvil@space_star ~]$

Same as above: the shell does word splitting on the result of command
substitution, and what it sees is the command (spaced for readability)

ls   hello-\   world
     ^^^^^^^   ^^^^^
      arg1      arg2

since those files or directory do not exist, ls correctly produces an error.

In both cases what you're seeing is not a bug, but just expected behavior.

-- 
D.