#!/usr/bin/perl

sub process_scheme{
    my ($cmd, $output_file) = @_;
    open (OUTPUT_FILE, ">", $output_file) || die "cannot open log file";
    my $scheme_pid = open (WORKER, "$cmd |") 
         || die "cannot pipe worker";
    my $str;
    while (1) {
        if (eof(WORKER)){    
            close WORKER;
            close OUTPUT;
            return 1;
        }

        eval{
            local $SIG{ALRM} = sub { die "alarm\n" }; # NB: \n required
            alarm 1;
            $str = <WORKER>;
            alarm 0;
        };
        if ($@) {
            close OUTPUT_FILE;
            close WORKER;
            return 0;
        }

        print OUTPUT_FILE $str;
    }
}

my $code = '$|=1; my $t=2; for (1..100) { printf "%.1f\n", $_*$t; select undef,undef,undef,$t; }';
my $cmd  = "perl -e '$code'";
process_scheme($cmd, "test.out");

##</code><code>##

$ strace -tttf ./811706.pl

##</code><code>##

...
[pid  7341] 1260280139.166408 write(1, "2.0\n", 4 <unfinished ...>
[pid  7340] 1260280139.166437 <... read resumed> "2.0\n", 4096) = 4
[pid  7340] 1260280139.166504 rt_sigaction(SIGALRM, NULL, {SIG_DFL}, 8) = 0
[pid  7340] 1260280139.166564 rt_sigprocmask(SIG_BLOCK, [ALRM], [], 8) = 0
[pid  7340] 1260280139.166614 rt_sigaction(SIGALRM, {SIG_DFL}, {SIG_DFL}, 8) = 0
[pid  7340] 1260280139.166648 rt_sigprocmask(SIG_SETMASK, [], NULL, 8) = 0
[pid  7340] 1260280139.166678 rt_sigprocmask(SIG_BLOCK, [ALRM], [], 8) = 0
[pid  7340] 1260280139.166708 rt_sigaction(SIGALRM, {0x46ed80, [], SA_RESTORER, 0x2ac53d237140}, {SIG_DFL}, 8) = 0
[pid  7340] 1260280139.166744 rt_sigprocmask(SIG_SETMASK, [], NULL, 8) = 0
[pid  7340] 1260280139.166774 alarm(1)  = 0
[pid  7340] 1260280139.166814 alarm(0)  = 1
[pid  7340] 1260280139.166844 rt_sigprocmask(SIG_BLOCK, [ALRM], [], 8) = 0
[pid  7340] 1260280139.166875 rt_sigaction(SIGALRM, {SIG_DFL}, {0x46ed80, [], SA_RESTORER, 0x2ac53d237140}, 8) = 0
[pid  7340] 1260280139.166910 rt_sigprocmask(SIG_SETMASK, [], NULL, 8) = 0
[pid  7340] 1260280139.166950 read(6,  <unfinished ...>
[pid  7341] 1260280139.166965 <... write resumed> ) = 4
[pid  7341] 1260280139.166990 select(0, NULL, NULL, NULL, {2, 0}) = 0 (Timeout)
[pid  7341] 1260280141.168299 write(1, "4.0\n", 4) = 4
[pid  7341] 1260280141.168344 select(0, NULL, NULL, NULL, {2, 0} <unfinished ...>
[pid  7340] 1260280141.168370 <... read resumed> "4.0\n", 4096) = 4
[pid  7340] 1260280141.168413 rt_sigprocmask(SIG_BLOCK, [ALRM], [], 8) = 0
[pid  7340] 1260280141.168461 rt_sigaction(SIGALRM, {SIG_DFL}, {SIG_DFL}, 8) = 0
[pid  7340] 1260280141.168501 rt_sigprocmask(SIG_SETMASK, [], NULL, 8) = 0
[pid  7340] 1260280141.168532 rt_sigprocmask(SIG_BLOCK, [ALRM], [], 8) = 0
[pid  7340] 1260280141.168566 rt_sigaction(SIGALRM, {0x46ed80, [], SA_RESTORER, 0x2ac53d237140}, {SIG_DFL}, 8) = 0
[pid  7340] 1260280141.168611 rt_sigprocmask(SIG_SETMASK, [], NULL, 8) = 0
[pid  7340] 1260280141.168640 alarm(1)  = 0
[pid  7340] 1260280141.168675 alarm(0)  = 1
...