Re: RFE: a way to echo the arguments with quoting

[Eduardo A . Bustamante López]

On Sat, Mar 01, 2014 at 02:34:56PM -0800, Dave Yost wrote:
> I have an ugly function I wrote for zsh that does this:
> 
> Sat 14:17:25 ip2 yost /Users/yost
> 1 634 Z% echo-quoted xyz \$foo  'a b c ' '\n'
> xyz '$foo' 'a b c ' '\n'
> Sat 14:17:53 ip2 yost /Users/yost
> 0 635 Z% 
> 
> It would be nice if there were an easy way to do this in bash.
> 
> Here is my use case:
> 
> echo-command() {
>       echo        -n 1>&2 "[ "
>       echo-quoted -n 1>&2    $@
>       echo           1>&2     " ]"
> }
> 
> echodo() {
>       echo-command $@
>       eval "$@"
> }
> 
> 1 652 Z% echodo sleep 1     
> [ sleep 1 ]
> 0 653 Z% 
> 
> This is a bit of a hack because when I need to use a pipe character, for 
> example, I have to quote it, and that gets echoed in a way that’s wrong for 
> this purpose.
> 
> 0 656 Z% echodo echo abc \| sed 's,b,_,'
> [ echo abc '|' sed s,b,_, ]
> a_c
> 0 657 Z% 
> 
> A builtin that does my ‘echodo’ without having to escape command-line 
> metacharacters is what I really want.
> 
> Is there such a thing?

(1) This list is for bug reports. If you need help with bash
scripting, consider using the help-bash mailing list.

(2) It's easier to achieve this using the DEBUG trap:

| address@hidden:~$ trap 'echo "$BASH_COMMAND"' DEBUG
| address@hidden:~$ echo foo >/dev/null
| echo foo > /dev/null
| address@hidden:~$ echo hello
| echo hello
| hello

(3) If you need 'eval' to achieve something in the shell, you're most
likely doing it wrong: http://mywiki.wooledge.org/BashFAQ/048

(4) For more advanced discussion regarding how to log commands to be
executed:
http://mywiki.wooledge.org/BashFAQ/050#I_want_a_log_of_my_script.27s_actions

But using the DEBUG trap should suffice, it's really advanced. If you
need to propagate that trap to children, use set -T and read about
shopt -s extdebug


Also, again, use help-bash for scripting questions.

-- 
Eduardo Alan Bustamante López