Getting `Can't exec "command"` error on zsh on alpine linux from inside a perl script - perl

Question

I've got a perl wrapper script for taskwarrior's task command that runs perfectly fine on macos.
I've ported it to a docker container running alpine. When I run the script, I get this weird error:
> # bin/task_wrapper.pl task list
Wrapper command: command task list
Can't exec "command": No such file or directory at bin/task_wrapper.pl line 61.
On my mac, it works just fine, no error.
which command reports: command: shell built-in command on both mac and on docker alpine.
I can run command task list directly from the command line in docker container and works fine.
Here's the whole script:
#! /usr/bin/env perl
use strict;
use warnings;
my $context;
my $runsub = shift #ARGV;
my #show_cmds = qw( done delete add modify );
{ no strict 'refs';
&${runsub}(#ARGV) if $runsub;
}
# my #tw_cmds = qw ( add annotate append calc config context count delete denotate done duplicate edit execute export help import log logo modify prepend purge start stop synchronize undo version );
my #descriptors = qw ( due: dep: depends: attribute: status: priority: pri: due: after: start: before: end: );
sub _parse {
my #bits = #_;
# find the first element that contains a command
my $count = 0;
my #ids;
my #rest = #bits;
foreach my $b (#bits) {
if ( $b =~ /([[a-f][0-9]]{8}),*/ ) {
push #ids, $1;
shift #rest;
next;
}
if ( $b =~ /(\d[\d\-]*),*/ ) {
push #ids, $1;
shift #rest;
next;
}
last;
}
return \#ids, \#rest;
}
sub task {
my $args = $_[0] || '';
my $filter = '';
my $subcmd = '';
if (ref $args) {
$filter = %$args{'filter'} || '';
$subcmd = %$args{'subcmd'} || '';
shift #_;
}
my #args = #_;
my #a = qw ( command task );
$context = $ENV{FLEXIBLE_CONTEXT} if !$context;
if ($context && $args ne 'sync') {
push #a, 'rc.context=' . $context;
}
if ($args =~ /sync/) {
exec 'command task sync';
} else {
print "Wrapper command: #a $filter $subcmd #args \n";
################ ERROR ON LINE BELOW
system("#a $filter $subcmd #args");
################
}
# show updated list of tasks
my $show;
$show = grep { $subcmd eq $_ } #show_cmds if $subcmd;
if ($show) {
my #sub_args;
push #sub_args, 'limit:3' if !$context;
push (#sub_args, '+st') if $context && $context !~ /\+sn|\+st/;
task ({}, #sub_args);
}
#print #a;
#print $ENV{FLEXIBLE_CONTEXT};
return;
}
sub ta {
task ({subcmd => 'add' }, #_ );
}
sub tm {
my ($ids, $rest) = _parse(#_);
task ({subcmd => 'modify', filter => "#$ids"}, #$rest);
}
# delete task
sub tdel {
my ($ids, $rest) = _parse(#_);
task ({subcmd => 'delete', filter => "#$ids"}, #$rest);
}
# done task
sub td {
task ('done', #_);
}
sub tl {
task ('next', "\\($ENV{'PU'} or +qst\\)", "-BLOCKED", #_);
}
sub tai {
task ('add', $ENV{'PU'}, 'due:1h', #_);
}

Answer 1

You say you're using zsh, and zsh does have a builtin named command, but you're not using zsh. You're using /bin/sh since
system( SHELL_CMD )
is effectively short for
system( '/bin/sh', '-c', SHELL_CMD )
(It's technically the value returned by perl -V:sh, not /bin/sh. But that value is /bin/sh.)
If you want to issue a zsh command, you will need to run zsh instead of /bin/sh.
system( 'zsh', '-c', SHELL_CMD )
Note that "#a $filter $subcmd #args" is not the proper way to build a shell command. It suffers from code injection bugs. You should use String::ShellQuote's shell_quote.