[英]How can I open a binary file in Perl, change ONLY the first byte, and write it back out?
open my $fh, '+<', $file or die "open failed: $!\n";
my $byte;
sysread($fh, $byte, 1) == 1 or die "read failed: $!\n";
seek($fh, 0, 0);
syswrite($fh, $new_byte) == 1 or die "write failed: $!\n";
close $fh or die "close failed: $!\n";
有很多方法可以做到。 一种有效的方法是以随机访问模式打开文件, open $fh, '+<'
:
my $first_byte = chr(14); # or whatever you want the first byte to be
open my $fh, '+<', $the_file;
seek $fh, 0, 0; # optional - cursor is originally set to 0
print $fh $first_byte; # could also use write or syswrite functions
close $fh;
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