会python真的可以为所欲为0(回)
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这里还有人吗1(回)
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544天前
每天面对着电脑屏幕，敲打键盘。我所面对的并不只是代码，而是一种生活方式。0(回)
769天前到处都是羊，不想上班0(回)
849天前
鸽子
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853天前#----------------------------- |
open(FH, "+< $path") or die "can't open $path: $!"; |
flock(FH, 2) or die "can't flock $path: $!"; |
# update file, then... |
close(FH) or die "can't close $path: $!"; |
#----------------------------- |
sub LOCK_SH() { 1 } # Shared lock (for reading) |
sub LOCK_EX() { 2 } # Exclusive lock (for writing) |
sub LOCK_NB() { 4 } # Non-blocking request (don't stall) |
sub LOCK_UN() { 8 } # Free the lock (careful!) |
#----------------------------- |
unless (flock(FH, LOCK_EX|LOCK_NB)) { |
warn "can't immediately write-lock the file ($!), blocking ..."; |
unless (flock(FH, LOCK_EX)) { |
die "can't get write-lock on numfile: $!"; |
} |
} |
#----------------------------- |
if ($] < 5.004) { # test Perl version number |
my $old_fh = select(FH); |
local $| = 1; # enable command buffering |
local $\ = ''; # clear output record separator |
print ""; # trigger output flush |
select($old_fh); # restore previous filehandle |
} |
flock(FH, LOCK_UN); |
#----------------------------- |
use Fcntl qw(:DEFAULT :flock); |
sysopen(FH, "numfile", O_RDWR|O_CREAT) |
or die "can't open numfile: $!"; |
flock(FH, LOCK_EX) or die "can't write-lock numfile: $!"; |
# Now we have acquired the lock, it's safe for I/O |
$num = <FH> || 0; # DO NOT USE "or" THERE!! |
seek(FH, 0, 0) or die "can't rewind numfile : $!"; |
truncate(FH, 0) or die "can't truncate numfile: $!"; |
print FH $num+1, "\n" or die "can't write numfile: $!"; |
close(FH) or die "can't close numfile: $!"; |
#----------------------------- |
