I'm attempting to print to standard out from the following Perl script, but it doesn't produce any output on the screen. It does print to a file, however.
#!/usr/bin/perl
use warnings;
use strict;
print "Here's some text\n";
print STDERR "Here's some text\n";
print STDOUT "Here's some text\n";
open FH, ">", "file.txt" or die $!;
print FH "Here's some text\n";
I tried checking the version of perl I'm using (perl -v), but that doesn't output anything either. The perl man page tells me I'm using 5.14.2. I'm running the Perl script from a bash prompt from a Raspberry Pi.
I saw this similar post Print: producing no output, so I used strace and saw that the output did not include any write commands.
strace perl -we'print("a") or die("Can'\''t print: $!\n");'
Here's the strace output for the full script:
execve("./response", ["./response"], [/* 18 vars */]) = 0
brk(0) = 0xd98000
uname({sys="Linux", node="raspberrypi", ...}) = 0
access("/etc/ld.so.nohwcap", F_OK) = -1 ENOENT (No such file or directory)
mmap2(NULL, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0xb6f99000
access("/etc/ld.so.preload", R_OK) = 0
open("/etc/ld.so.preload", O_RDONLY) = 3
fstat64(3, {st_mode=S_IFREG|0644, st_size=44, ...}) = 0
mmap2(NULL, 44, PROT_READ|PROT_WRITE, MAP_PRIVATE, 3, 0) = 0xb6f98000
close(3) = 0
open("/usr/lib/arm-linux-gnueabihf/libcofi_rpi.so", O_RDONLY) = 3
read(3, "\177ELF\1\1\1\0\0\0\0\0\0\0\0\0\3\0(\0\1\0\0\0\270\4\0\0004\0\0\0"..., 512) = 512
lseek(3, 7276, SEEK_SET) = 7276
read(3, "\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"..., 1080) = 1080
lseek(3, 7001, SEEK_SET) = 7001
read(3, "A.\0\0\0aeabi\0\1$\0\0\0\0056\0\6\6\10\1\t\1\n\2\22\4\24\1\25"..., 47) = 47
fstat64(3, {st_mode=S_IFREG|0755, st_size=10170, ...}) = 0
mmap2(NULL, 39740, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0xb6f6c000
mprotect(0xb6f6e000, 28672, PROT_NONE) = 0
mmap2(0xb6f75000, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x1) = 0xb6f75000
close(3) = 0
munmap(0xb6f98000, 44) = 0
open("/etc/ld.so.cache", O_RDONLY) = 3
fstat64(3, {st_mode=S_IFREG|0644, st_size=64456, ...}) = 0
mmap2(NULL, 64456, PROT_READ, MAP_PRIVATE, 3, 0) = 0xb6f5c000
close(3) = 0
access("/etc/ld.so.nohwcap", F_OK) = -1 ENOENT (No such file or directory)
open("/usr/lib/libperl.so.5.14", O_RDONLY) = 3
read(3, "\177ELF\1\1\1\0\0\0\0\0\0\0\0\0\3\0(\0\1\0\0\0\220\v\2\0004\0\0\0"..., 512) = 512
lseek(3, 1346508, SEEK_SET) = 1346508
read(3, "\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"..., 1120) = 1120
lseek(3, 1346184, SEEK_SET) = 1346184
read(3, "A2\0\0\0aeabi\0\1(\0\0\0\0056\0\6\6\10\1\t\1\n\2\22\4\24\1\25"..., 51) = 51
fstat64(3, {st_mode=S_IFREG|0644, st_size=1347628, ...}) = 0
mmap2(NULL, 1379192, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0xb6e0b000
mprotect(0xb6f4f000, 32768, PROT_NONE) = 0
mmap2(0xb6f57000, 20480, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x144) = 0xb6f57000
close(3) = 0
access("/etc/ld.so.nohwcap", F_OK) = -1 ENOENT (No such file or directory)
open("/lib/arm-linux-gnueabihf/libdl.so.2", O_RDONLY) = 3
read(3, "\177ELF\1\1\1\0\0\0\0\0\0\0\0\0\3\0(\0\1\0\0\0(\t\0\0004\0\0\0"..., 512) = 512
lseek(3, 8652, SEEK_SET) = 8652
read(3, "\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"..., 1160) = 1160
lseek(3, 8320, SEEK_SET) = 8320
read(3, "A0\0\0\0aeabi\0\1&\0\0\0\0056\0\6\6\10\1\t\1\n\2\22\4\24\1\25"..., 49) = 49
fstat64(3, {st_mode=S_IFREG|0644, st_size=9812, ...}) = 0
mmap2(NULL, 41136, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0xb6e00000
mprotect(0xb6e02000, 28672, PROT_NONE) = 0
mmap2(0xb6e09000, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x1) = 0xb6e09000
close(3) = 0
access("/etc/ld.so.nohwcap", F_OK) = -1 ENOENT (No such file or directory)
open("/lib/arm-linux-gnueabihf/libm.so.6", O_RDONLY) = 3
read(3, "\177ELF\1\1\1\0\0\0\0\0\0\0\0\0\3\0(\0\1\0\0\0\3201\0\0004\0\0\0"..., 512) = 512
lseek(3, 426468, SEEK_SET) = 426468
read(3, "\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"..., 1160) = 1160
lseek(3, 426136, SEEK_SET) = 426136
read(3, "A0\0\0\0aeabi\0\1&\0\0\0\0056\0\6\6\10\1\t\1\n\2\22\4\24\1\25"..., 49) = 49
fstat64(3, {st_mode=S_IFREG|0644, st_size=427628, ...}) = 0
mmap2(NULL, 458912, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0xb6d8f000
mprotect(0xb6df7000, 28672, PROT_NONE) = 0
mmap2(0xb6dfe000, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x67) = 0xb6dfe000
close(3) = 0
access("/etc/ld.so.nohwcap", F_OK) = -1 ENOENT (No such file or directory)
open("/lib/arm-linux-gnueabihf/libpthread.so.0", O_RDONLY) = 3
read(3, "\177ELF\1\1\1\0\0\0\0\0\0\0\0\0\3\0(\0\1\0\0\0\274V\0\0004\0\0\0"..., 512) = 512
lseek(3, 82712, SEEK_SET) = 82712
read(3, "\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"..., 1400) = 1400
lseek(3, 82308, SEEK_SET) = 82308
read(3, "A0\0\0\0aeabi\0\1&\0\0\0\0056\0\6\6\10\1\t\1\n\2\22\4\24\1\25"..., 49) = 49
fstat64(3, {st_mode=S_IFREG|0755, st_size=116462, ...}) = 0
mmap2(NULL, 123412, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0xb6d70000
mprotect(0xb6d84000, 28672, PROT_NONE) = 0
mmap2(0xb6d8b000, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x13) = 0xb6d8b000
mmap2(0xb6d8d000, 4628, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0xb6d8d000
close(3) = 0
access("/etc/ld.so.nohwcap", F_OK) = -1 ENOENT (No such file or directory)
open("/lib/arm-linux-gnueabihf/libc.so.6", O_RDONLY) = 3
read(3, "\177ELF\1\1\1\0\0\0\0\0\0\0\0\0\3\0(\0\1\0\0\0\214y\1\0004\0\0\0"..., 512) = 512
lseek(3, 1215264, SEEK_SET) = 1215264
read(3, "\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"..., 1360) = 1360
lseek(3, 1214828, SEEK_SET) = 1214828
read(3, "A.\0\0\0aeabi\0\1$\0\0\0\0056\0\6\6\10\1\t\1\n\2\22\4\24\1\25"..., 47) = 47
fstat64(3, {st_mode=S_IFREG|0755, st_size=1216624, ...}) = 0
mmap2(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0xb6f98000
mmap2(NULL, 1258784, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0xb6c3c000
mprotect(0xb6d62000, 32768, PROT_NONE) = 0
mmap2(0xb6d6a000, 12288, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x126) = 0xb6d6a000
mmap2(0xb6d6d000, 9504, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0xb6d6d000
close(3) = 0
access("/etc/ld.so.nohwcap", F_OK) = -1 ENOENT (No such file or directory)
open("/lib/arm-linux-gnueabihf/libcrypt.so.1", O_RDONLY) = 3
read(3, "\177ELF\1\1\1\0\0\0\0\0\0\0\0\0\3\0(\0\1\0\0\0\30\7\0\0004\0\0\0"..., 512) = 512
lseek(3, 29116, SEEK_SET) = 29116
read(3, "\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"..., 1160) = 1160
lseek(3, 28780, SEEK_SET) = 28780
read(3, "A0\0\0\0aeabi\0\1&\0\0\0\0056\0\6\6\10\1\t\1\n\2\22\4\24\1\25"..., 49) = 49
fstat64(3, {st_mode=S_IFREG|0644, st_size=30276, ...}) = 0
mmap2(NULL, 221504, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0xb6c05000
mprotect(0xb6c0c000, 28672, PROT_NONE) = 0
mmap2(0xb6c13000, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x6) = 0xb6c13000
mmap2(0xb6c15000, 155968, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0xb6c15000
close(3) = 0
access("/etc/ld.so.nohwcap", F_OK) = -1 ENOENT (No such file or directory)
open("/lib/arm-linux-gnueabihf/libgcc_s.so.1", O_RDONLY) = 3
read(3, "\177ELF\1\1\1\0\0\0\0\0\0\0\0\0\3\0(\0\1\0\0\0`\364\0\0004\0\0\0"..., 512) = 512
lseek(3, 130212, SEEK_SET) = 130212
read(3, "\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"..., 1160) = 1160
lseek(3, 129880, SEEK_SET) = 129880
read(3, "A2\0\0\0aeabi\0\1(\0\0\0\0056\0\6\6\10\1\t\1\n\2\22\4\24\1\25"..., 51) = 51
fstat64(3, {st_mode=S_IFREG|0644, st_size=131372, ...}) = 0
mmap2(NULL, 162704, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0xb6bdd000
mprotect(0xb6bfd000, 28672, PROT_NONE) = 0
mmap2(0xb6c04000, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x1f) = 0xb6c04000
close(3) = 0
mmap2(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0xb6f97000
set_tls(0xb6f976d0, 0xb6f97da8, 0xb6f9c048, 0xb6f976d0, 0xb6f9c048) = 0
mprotect(0xb6c13000, 4096, PROT_READ) = 0
mprotect(0xb6d6a000, 8192, PROT_READ) = 0
mprotect(0xb6d8b000, 4096, PROT_READ) = 0
mprotect(0xb6dfe000, 4096, PROT_READ) = 0
mprotect(0xb6e09000, 4096, PROT_READ) = 0
mprotect(0xb6f57000, 8192, PROT_READ) = 0
mprotect(0x11000, 4096, PROT_READ) = 0
mprotect(0xb6f9b000, 4096, PROT_READ) = 0
munmap(0xb6f5c000, 64456) = 0
set_tid_address(0xb6f97278) = 12607
set_robust_list(0xb6f97280, 0xc) = 0
futex(0xbece6778, FUTEX_WAIT_BITSET_PRIVATE|FUTEX_CLOCK_REALTIME, 1, NULL, b6d8c000) = -1 EAGAIN (Resource temporarily unavailable)
rt_sigaction(SIGRTMIN, {0xb6d7520c, [], SA_SIGINFO|0x4000000}, NULL, 8) = 0
rt_sigaction(SIGRT_1, {0xb6d750b4, [], SA_RESTART|SA_SIGINFO|0x4000000}, NULL, 8) = 0
rt_sigprocmask(SIG_UNBLOCK, [RTMIN RT_1], NULL, 8) = 0
getrlimit(RLIMIT_STACK, {rlim_cur=8192*1024, rlim_max=RLIM_INFINITY}) = 0
rt_sigaction(SIGFPE, {SIG_IGN, [FPE], SA_RESTART|0x4000000}, {SIG_DFL, [], 0}, 8) = 0
brk(0) = 0xd98000
brk(0xdb9000) = 0xdb9000
getuid32() = 1001
geteuid32() = 1001
getgid32() = 1004
getegid32() = 1004
open("/usr/lib/locale/locale-archive", O_RDONLY|O_LARGEFILE) = 3
fstat64(3, {st_mode=S_IFREG|0644, st_size=1534656, ...}) = 0
mmap2(NULL, 1534656, PROT_READ, MAP_PRIVATE, 3, 0) = 0xb6a66000
close(3) = 0
open("/dev/urandom", O_RDONLY|O_LARGEFILE) = 3
read(3, "~\210\223\234", 4) = 4
close(3) = 0
gettimeofday({1460938704, 307768}, NULL) = 0
readlink("/proc/self/exe", "/usr/bin/perl", 4095) = 13
stat64("/usr/local/lib/site_perl/5.14.2/arm-linux-gnueabihf-thread-multi-64int", 0xbece6368) = -1 ENOENT (No such file or directory)
stat64("/usr/local/lib/site_perl/5.14.2", 0xbece6368) = -1 ENOENT (No such file or directory)
stat64("/usr/local/lib/site_perl/arm-linux-gnueabihf-thread-multi-64int", 0xbece6368) = -1 ENOENT (No such file or directory)
open("./response", O_RDONLY|O_LARGEFILE) = 3
ioctl(3, SNDCTL_TMR_TIMEBASE or TCGETS, 0xbece627c) = -1 ENOTTY (Inappropriate ioctl for device)
_llseek(3, 0, [0], SEEK_CUR) = 0
fcntl64(3, F_SETFD, FD_CLOEXEC) = 0
rt_sigaction(SIGCHLD, NULL, {SIG_DFL, [], 0}, 8) = 0
brk(0xddb000) = 0xddb000
read(3, "#!/usr/bin/perl\nuse warnings;\nus"..., 8192) = 210
stat64("/etc/perl/warnings.pmc", 0xbece5e10) = -1 ENOENT (No such file or directory)
stat64("/etc/perl/warnings.pm", 0xbece5d90) = -1 ENOENT (No such file or directory)
stat64("/usr/local/lib/perl/5.14.2/warnings.pmc", 0xbece5e10) = -1 ENOENT (No such file or directory)
stat64("/usr/local/lib/perl/5.14.2/warnings.pm", 0xbece5d90) = -1 ENOENT (No such file or directory)
stat64("/usr/local/share/perl/5.14.2/warnings.pmc", 0xbece5e10) = -1 ENOENT (No such file or directory)
stat64("/usr/local/share/perl/5.14.2/warnings.pm", 0xbece5d90) = -1 ENOENT (No such file or directory)
stat64("/usr/lib/perl5/warnings.pmc", 0xbece5e10) = -1 ENOENT (No such file or directory)
stat64("/usr/lib/perl5/warnings.pm", 0xbece5d90) = -1 ENOENT (No such file or directory)
stat64("/usr/share/perl5/warnings.pmc", 0xbece5e10) = -1 ENOENT (No such file or directory)
stat64("/usr/share/perl5/warnings.pm", 0xbece5d90) = -1 ENOENT (No such file or directory)
stat64("/usr/lib/perl/5.14/warnings.pmc", 0xbece5e10) = -1 ENOENT (No such file or directory)
stat64("/usr/lib/perl/5.14/warnings.pm", 0xbece5d90) = -1 ENOENT (No such file or directory)
stat64("/usr/share/perl/5.14/warnings.pmc", 0xbece5e10) = -1 ENOENT (No such file or directory)
stat64("/usr/share/perl/5.14/warnings.pm", {st_mode=S_IFREG|0644, st_size=15015, ...}) = 0
open("/usr/share/perl/5.14/warnings.pm", O_RDONLY|O_LARGEFILE) = 4
ioctl(4, SNDCTL_TMR_TIMEBASE or TCGETS, 0xbece5be4) = -1 ENOTTY (Inappropriate ioctl for device)
_llseek(4, 0, [0], SEEK_CUR) = 0
read(4, "# -*- buffer-read-only: t -*-\n# "..., 8192) = 8192
read(4, "08\\x00\\x00\\x00\\x00\\x00\\x00\\x00\\x"..., 8192) = 6823
read(4, "", 8192) = 0
close(4) = 0
brk(0xdfc000) = 0xdfc000
stat64("/etc/perl/strict.pmc", 0xbece5e10) = -1 ENOENT (No such file or directory)
stat64("/etc/perl/strict.pm", 0xbece5d90) = -1 ENOENT (No such file or directory)
stat64("/usr/local/lib/perl/5.14.2/strict.pmc", 0xbece5e10) = -1 ENOENT (No such file or directory)
stat64("/usr/local/lib/perl/5.14.2/strict.pm", 0xbece5d90) = -1 ENOENT (No such file or directory)
stat64("/usr/local/share/perl/5.14.2/strict.pmc", 0xbece5e10) = -1 ENOENT (No such file or directory)
stat64("/usr/local/share/perl/5.14.2/strict.pm", 0xbece5d90) = -1 ENOENT (No such file or directory)
stat64("/usr/lib/perl5/strict.pmc", 0xbece5e10) = -1 ENOENT (No such file or directory)
stat64("/usr/lib/perl5/strict.pm", 0xbece5d90) = -1 ENOENT (No such file or directory)
stat64("/usr/share/perl5/strict.pmc", 0xbece5e10) = -1 ENOENT (No such file or directory)
stat64("/usr/share/perl5/strict.pm", 0xbece5d90) = -1 ENOENT (No such file or directory)
stat64("/usr/lib/perl/5.14/strict.pmc", 0xbece5e10) = -1 ENOENT (No such file or directory)
stat64("/usr/lib/perl/5.14/strict.pm", 0xbece5d90) = -1 ENOENT (No such file or directory)
stat64("/usr/share/perl/5.14/strict.pmc", 0xbece5e10) = -1 ENOENT (No such file or directory)
stat64("/usr/share/perl/5.14/strict.pm", {st_mode=S_IFREG|0644, st_size=879, ...}) = 0
open("/usr/share/perl/5.14/strict.pm", O_RDONLY|O_LARGEFILE) = 4
ioctl(4, SNDCTL_TMR_TIMEBASE or TCGETS, 0xbece5be4) = -1 ENOTTY (Inappropriate ioctl for device)
_llseek(4, 0, [0], SEEK_CUR) = 0
read(4, "package strict;\n\n$strict::VERSIO"..., 8192) = 879
_llseek(4, 878, [878], SEEK_SET) = 0
_llseek(4, 0, [878], SEEK_CUR) = 0
close(4) = 0
read(3, "", 8192) = 0
open("file.txt", O_WRONLY|O_CREAT|O_TRUNC|O_LARGEFILE, 0666) = 4
ioctl(4, SNDCTL_TMR_TIMEBASE or TCGETS, 0xbece614c) = -1 ENOTTY (Inappropriate ioctl for device)
_llseek(4, 0, [0], SEEK_CUR) = 0
fstat64(4, {st_mode=S_IFREG|0644, st_size=0, ...}) = 0
fcntl64(4, F_SETFD, FD_CLOEXEC) = 0
rt_sigaction(SIG_0, NULL, {0xb6e18dc4, [TRAP RTMIN RT_1 RT_2 RT_3 RT_12 RT_13 RT_15 RT_16 RT_18 RT_19 RT_20 RT_25 RT_26 RT_27 RT_28 RT_29], SA_SIGINFO|0x85b8}, 8) = -1 EINVAL (Invalid argument)
rt_sigaction(SIGHUP, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigaction(SIGINT, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigaction(SIGQUIT, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigaction(SIGILL, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigaction(SIGTRAP, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigaction(SIGABRT, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigaction(SIGBUS, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigaction(SIGFPE, NULL, {SIG_IGN, [FPE], SA_RESTART|0x4000000}, 8) = 0
rt_sigaction(SIGKILL, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigaction(SIGUSR1, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigaction(SIGSEGV, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigaction(SIGUSR2, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigaction(SIGPIPE, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigaction(SIGALRM, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigaction(SIGTERM, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigaction(SIGSTKFLT, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigaction(SIGCHLD, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigaction(SIGCONT, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigaction(SIGSTOP, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigaction(SIGTSTP, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigaction(SIGTTIN, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigaction(SIGTTOU, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigaction(SIGURG, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigaction(SIGXCPU, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigaction(SIGXFSZ, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigaction(SIGVTALRM, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigaction(SIGPROF, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigaction(SIGWINCH, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigaction(SIGIO, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigaction(SIGPWR, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigaction(SIGSYS, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigaction(SIGRT_2, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigaction(SIGRT_3, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigaction(SIGRT_4, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigaction(SIGRT_5, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigaction(SIGRT_6, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigaction(SIGRT_7, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigaction(SIGRT_8, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigaction(SIGRT_9, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigaction(SIGRT_10, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigaction(SIGRT_11, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigaction(SIGRT_12, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigaction(SIGRT_13, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigaction(SIGRT_14, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigaction(SIGRT_15, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigaction(SIGRT_16, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigaction(SIGRT_17, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigaction(SIGRT_18, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigaction(SIGRT_19, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigaction(SIGRT_20, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigaction(SIGRT_21, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigaction(SIGRT_22, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigaction(SIGRT_23, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigaction(SIGRT_24, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigaction(SIGRT_25, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigaction(SIGRT_26, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigaction(SIGRT_27, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigaction(SIGRT_28, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigaction(SIGRT_29, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigaction(SIGRT_30, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigaction(SIGRT_31, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigaction(SIGRT_32, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigaction(SIGABRT, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigaction(SIGCHLD, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigaction(SIGIO, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigaction(SIGSYS, NULL, {SIG_DFL, [], 0}, 8) = 0
write(4, "Here's some text\n", 17) = 17
close(4) = 0
close(3) = 0
exit_group(0) = ?
Any ideas about why it's not producing output? A bash script can echo text to standard out just fine.
当我在调试模式下运行脚本时,它会打印输出.
在命令行执行perl -v后退出代码来自$？是0.
执行
perl -e'print "foo" or die $!'
给出并退出代码9,但这似乎是由于死亡.perl -v>文件没有写任何文件.
以下是stat STDOUT的输出以及用于将其写入文件的命令:
45826 | 261126 | 33188 | 1 | 1001 | 1004 | 0 | 0 | 1461024408 | 1461035504 | 1461035504 | 4096 | 0
perl -e 'open my $FH, ">file"; print $FH join "|", stat STDOUT '
在开始阅读之前看一下这个命令的输出.一切都指向STDOUT指向错误的地方.
ls -l /proc/$$/fd/{1,2}
在我的系统上,我得到了这个,注意它在我写这个时确实发生了变化,因为这不是一次性编写的.
lrwx------ 1 root root 64 May 3 17:01 /proc/27806/fd/1 -> /dev/pts/1
lrwx------ 1 root root 64 May 3 17:01 /proc/27806/fd/2 -> /dev/pts/1
我怀疑上面的内容与你相似.对我来说,stat看起来很可疑,如果我有权访问filesytem,我会搜索它正在告诉我写入的文件.
sudo find / -printf "%i:\t%p\n"|grep 261126
如果当Perl开始将它的stdout等更改为错误的地方时,我会在脚本中添加一个很长的睡眠,然后进行搜索以查看它的位置.如果文件是常规文件,并且它位于文件系统上,则应该找到它.
我对STDOUT的统计
|dev |inode |mode |link |uid |gid |rdev |size |atime |mtime |ctime |blk |blka
|13 |3 |8592 |1 |1000|5 |34816|0 |1462301986|1462301986|1462301958|1024|0
关于STDOUT的统计数据
|dev |inode |mode |link |uid |gid |rdev |size |atime |mtime |ctime |blk |blka
|45826 |261126 |33188 |1 |1001|1004|0 |0 |1461024408|1461035504|1461035504|4096|0
在我的dev手机上我有次要的13号,当我在设备下搜索它时看起来不错.如果我们掩饰你的主要/次要你有......
major == 179
minor == 2
请注意,我最初将这些反过来直到被Wumpus Q.Wumbley纠正.
在我的机器上这是
crw------- 1 root root 2, 179 Apr 29 12:50 ptya3
我的rdev等同于我的
major == 136
minor == 0
在我的Debian系统上,这是/dev/pts/0.你rdev是0.我快速看了一下,有些人使用屏幕可能有问题,/dev/pts/N即它不存在,但这是我的猜测.
strace也很奇怪,我在系统上写的时候得到以下几行:
read(3, "#!/usr/bin/perl -w\n#use strict;\n"..., 8192) = 228
read(3, "", 8192) = 0
close(3) = 0
write(1, "Here's some text STDOUT\n", 24Here's some text STDOUT
) = 24
write(2, "Here's some text STDERR\n", 24Here's some text STDERR
) = 24
write(1, "Here's some text STDOUT\n", 24Here's some text STDOUT
) = 24
事实上,这些似乎没有在你的strace中确实是非常奇怪的.您可以通过搞乱来改变出现的位置,$|但它们应该出现在某个地方.吉尔斯注意到这种模式也很奇怪.如果你运行这个脚本......
#!/usr/bin/perl
use warnings;
use strict;
use Fcntl ':mode';
my $mode = 33188;
my $user_rwx = ($mode & S_IRWXU) >> 6;
print("user_rwx = $user_rwx\n");
my $group_read = ($mode & S_IRGRP) >> 3;
print("group_read = $group_read\n");
my $other_execute = $mode & S_IXOTH;
print("other_execute = $other_execute\n");
printf "Permissions are %04o\n", S_IMODE($mode), "\n";
my $is_setuid = $mode & S_ISUID;
print("is_setuid = $is_setuid\n");
my $is_directory = S_ISDIR($mode);
print("dir = $is_directory\n");
my $is_reg = S_ISREG($mode);
print("regular = $is_reg\n");
您可以看到STDOUT似乎指向常规文件.这将证实为什么rdev是零,即如果stdout重定向到一个本来就是设备但实际上只是一个普通文件的东西.我已经看到类似奇怪的事情发生在设备未正确设置的chrooted环境中.
无论在退出时缓冲是打开还是关闭,缓冲区都应该被刷新,即你会看到对write sys调用的调用.在strace中根本没有写入,这真的很奇怪.
$|=1尝试在您的行后添加use：
#!/usr/bin/perl
use warnings;
use strict;
$|=1;
print "Here's some text\n";
print STDERR "Here's some text\n";
print STDOUT "Here's some text\n";
open FH, ">", "file.txt" or die $!;
print FH "Here's some text\n";
strace 输出还显示，由于 Perl 的输出缓冲，打印到文件是在脚本退出时完成的，而不是在脚本运行时完成的。
如果$|=1没有帮助：尝试获取脚本使用的 FD：
#!/usr/bin/perl
system "ls -l /proc/$$/fd";
或者
#!/usr/bin/perl
system "lsof -p $$";
他们应该给你一个提示，输出应该去哪里。
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