Re: chomping the output of Shell.pm

[kcott]

G'day Rolf,

Update: I posted a solution but later found it didn't work with commands that output multiple lines (e.g. ls, ps, etc.). Here's a new solution that doesn't have that problem. The original also had a portability issue: this one doesn't. (The spoiler below contains the original solution.)

My .perldb contains:

$ cat ~/.perldb
for (qw{pwd date ls ps}) {
    $DB::alias{$_}
        = 's{^($_.*)$}{chomp(my $out = qx{$1}); print {$DB::OUT} $out}
+e';
}

Obviously, substitute qw{pwd date ls ps} with your qw/commands/. See perldebug - Debugger Customization for a description of %DB::alias.

Here's a test run:

$ perl -d -e 1

Loading DB routines from perl5db.pl version 1.33
Editor support available.

Enter h or `h h' for help, or `man perldebug' for more help.

main::(-e:1):    1
  DB<1> pwd
/Users/ken/tmp
  DB<2> date
Sun  9 Sep 2012 18:12:43 EST
  DB<3> date "%Y-%m-%d"
date: illegal time format
usage: date [-jnu] [-d dst] [-r seconds] [-t west] [-v[+|-]val[ymwdHMS
+]] ... 
            [-f fmt date | [[[mm]dd]HH]MM[[cc]yy][.ss]] [+format]

  DB<4> date "+%Y-%m-%d"
2012-09-09
  DB<5> ls -l
total 30824
...
drwxr-xr-x  7 ken  staff      238 14 Jun 20:23 zip_test
  DB<6> ps -ef
  UID   PID  PPID   C STIME   TTY           TIME CMD
  ...
  501 74528 74527   0 23Aug12 ttys007    0:00.04 -bash
  DB<7> q
$

The typo (date "%Y-%m-%d") was accidental but I left it in just to show that the mistake was handled in a reasonable fashion.

---

My original, faulty solution - don't use this!

Here's a technique that seems to work. I've only done limited testing. It doesn't use Shell or chomp. It also assumes that the shell command echo -n suppresses the output of trailing newlines.

My .perldb contains a single line:

$ cat ~/.perldb
$DB::alias{$_} = 's{^$_(.*)$}{p qx{$_$1 | xargs echo -n}}' for qw{pwd 
+date};

Obviously, substitute qw{pwd date} with your qw/commands/. See perldebug - Debugger Customization for a description of %DB::alias.

Here's a test run:

$ perl -d -e 1

Loading DB routines from perl5db.pl version 1.33
Editor support available.

Enter h or `h h' for help, or `man perldebug' for more help.

main::(-e:1):    1
  DB<1> pwd
/Users/ken/tmp
  DB<2> date
Sun 9 Sep 2012 14:22:23 EST
  DB<3> date "%Y-%m-%d"
date: illegal time format
usage: date [-jnu] [-d dst] [-r seconds] [-t west] [-v[+|-]val[ymwdHMS
+]] ... 
            [-f fmt date | [[[mm]dd]HH]MM[[cc]yy][.ss]] [+format]

  DB<4> date "+%Y-%m-%d"
2012-09-09
  DB<5> q

The typo (date "%Y-%m-%d") was accidental but I left it in just to show that the mistake was handled in a reasonable fashion.

[LanX]

Hi Ken,

thanks for your solution, but I wanna use those functions in any place not only at start of line.

e.g.

rm grep {/.pl$/} ls ¹

If you wanna implement (start of line) aliases, you should simply us "!!"

  DB<112> =du !!du
 
  DB<113> du /tmp
8    /tmp/pulse-lanx
4    /tmp/virtual-lanx.AqXwcf
...
  DB<114>  $DB::alias{du} 
 => "s\adu\a!!du\a"

!! cmd      Run cmd in a subprocess (reads from DB::IN, writes to DB::
+OUT)
        See 'O shellBang' too.

¹) Yes I could use the file-glob <*> instead, but this is only an example for chaining commands