system
, exec
, open '|-'
, open2
, etc. all allow me to specify the command to run as a list of arguments that will be passed directly to execvp
instead of run through a shell.
Even if perl
is smart enough to run it directly if it looks like a "simple" command, that saves me the trouble of correctly shell-escaping the arguments with all the nasty pitfalls that it entails.
Example:
open my $out, '|-', $prog, @args;
system $prog, @args;
exec $prog, @args;
instead of
open my $out, "|$prog @args";
system "$prog @args";
exec "$prog @args";
Is there such an equivalent for the qx//
operator? Or do you have to always do it by hand eg.
sub slurpcmd {
open my $h, '-|', @_ or die "open $_[0]|: $!";
local $/ unless wantarray;
<$h>
}
It turns out that (unfortunately) this wasn't an overlook from my part -- the only solution really is to do it with open -|
or use one of the external modules listed in the other answers.
The backtick implementation (whether invoked by qx/.../
, `...`
, or readpipe
) is deep down hardwired to accept a single string argument:
PP(pp_backtick)
{
dSP; dTARGET;
PerlIO *fp;
const char * const tmps = POPpconstx;
const U8 gimme = GIMME_V;
const char *mode = "r";
TAINT_PROPER("``");
if (PL_op->op_private & OPpOPEN_IN_RAW)
mode = "rb";
else if (PL_op->op_private & OPpOPEN_IN_CRLF)
mode = "rt";
fp = PerlProc_popen(tmps, mode);
...
Notice the POPpconstx
which pops a single argument from the stack and the use of PerlProc_popen
instead of PerlProc_popen_list
.