問題描述
在 Perl 中寫入文件的問題 (Issues writing to a file in Perl)
I am running this script on solaris. I am trying to write the real, user, and system times to a file, each on a separate line. However, this code instead writes them out together on the same line with a bunch of unknown character boxes. How can I get each of the times on their own separate line?
#!/usr/local/bin/perl ‑w
use strict;
use warnings;
my $command = "time echo 'hi' 2>&1 | tee ‑a runtimes.log";
system ($command);
‑‑‑‑‑
參考解法
方法 1:
Solaris standard line delimiter is \n, so your code seems right. Look also here.
Possibly your problem has to do with the text editor you are using to view the file...
方法 2:
Two things:
- Check the output of both your
openandsystemcommands. - Print an extra blank line before you close the file.
Try this:
#!/usr/bin/env perl
use strict;
use warnings; #No need for ‑w when using this
my $command = "time ls 2>&1 | tee ‑a runtimes.log";
open (FILE, '>>runtimes.log')
or die qq(Can't open "runtimes.log for writing\n);
my $error = system ($command);
if ($error) {
die qq(Error in executing command "$command": $?\n);
}
print "\n";
close FILE;
exit 0;
方法 3:
You'll probably get better results as well as more maintainable code if you use perl code (either times or POSIX::times) for getting the system/user times.
$command="ls ‑lR";
@before{real,user,system,chuser,chsystem}=(time(),times());
system $command;
@after{real,user,system,chuser,chsystem}=(time(),times());
print "real @{[ $after{real}‑$before{real} ]}\n";
print "user @{[ $after{chuser}‑$before{chuser} ]}\n";
print "sys @{[ $after{chsystem}‑$before{chsystem} ]}\n";
or the POSIX version:
use POSIX qw(times sysconf);
$clocks_per_second=POSIX::sysconf( &POSIX::_SC_CLK_TCK );
$command="ls ‑lR";
@before{real,user,system,chuser,chsystem}=(POSIX::times());
system $command;
@after{real,user,system,chuser,chsystem}=(POSIX::times());
printf "real %2.2f\n", ($after{real}‑$before{real})/$clocks_per_second;
printf "user %2.2f\n", ($after{chuser}‑$before{chuser})/$clocks_per_second;
printf "sys %2.2f\n", ($after{chsystem}‑$before{chsystem})/$clocks_per_second;
(by Stephen D、sergio、David W.、evil otto)