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$rc = system { "lskdfj" } "lskdfj"; unless( ok($rc == 255 << 8 or $rc == -1 or $rc == 256 or $rc == 512) ) + { print "# \$rc == $rc\n"; ... $! == 22 or $! =~ /invalid argument/i ) ) { printf "# \$! eq %d, '%s'\n", $!, $!; }