Hello Dunkellbusch,

Welcome to the Monastery. The monks have already provided you with solutions to your problem, but I would like to add one more. You can use the module File::Slurp/append_file, so you can minimize your code to simply one call in every time you need it, no closing file handles etc.

But to be honest I would combine the module with the nice solution of fellow monk Corion, executable sample bellow below (change grep from /enable/ to /smb\.service/):

#!/usr/bin/perl
use strict;
use warnings;
use File::Slurp;

my $filePath = 'test_1.txt';
my @services = `systemctl list-unit-files`;

if( my @smb = grep { /enabled/ } @services ) {
    map { s/\s+\z// } @smb; # remover white space
    append_file( $filePath, "chkconfig smb: OK\n");
    append_file( $filePath, map { "$_\n" } @smb);
    # append_file( $filePath, "\n"); # if you want to append multiple 
+times
}

[download]

Update: Based on comments try to avoid File::Slurp, for simple implementations (read, write, etc) you can use File::Slurper, unfortunately there the author has not added the append proposal. I was looking online and I found the IO::All. Never used it before but I read that it is really really good.

Sample of updated solution, based on commends:

#!/usr/bin/perl
use strict;
use warnings;
use IO::All -utf8;  # Turn on utf8 for all io

my $path = 'file.txt';
my @services = `systemctl list-unit-files`;

if( my @smb = grep { /enabled/ } @services ) {
    s{ ^\s* | \s*$ }{}gx for @smb;
    io($path)->appendln(@smb);
}

[download]

Output:

$ cat test_1.txt
chkconfig smb: OK
acpid.path                                 enabled
cups.path                                  enabled
accounts-daemon.service                    enabled
anacron-resume.service                     enabled
anacron.service                            enabled
apparmor.service                           enabled
autovt@.service                            enabled
avahi-daemon.service                       enabled
bluetooth.service                          enabled
console-setup.service                      enabled
cron.service                               enabled
cups-browsed.service                       enabled
cups.service                               enabled
dbus-org.bluez.service                     enabled
dbus-org.freedesktop.Avahi.service         enabled
dbus-org.freedesktop.ModemManager1.service enabled
dbus-org.freedesktop.nm-dispatcher.service enabled
dbus-org.freedesktop.resolve1.service      enabled
dbus-org.freedesktop.thermald.service      enabled
denyhosts.service                          enabled
display-manager.service                    enabled
dns-clean.service                          enabled
friendly-recovery.service                  enabled
getty@.service                             enabled
gpu-manager.service                        enabled
keyboard-setup.service                     enabled
lightdm.service                            enabled
ModemManager.service                       enabled
network-manager.service                    enabled
networking.service                         enabled
NetworkManager-dispatcher.service          enabled
NetworkManager-wait-online.service         enabled
NetworkManager.service                     enabled
ondemand.service                           enabled
openvpn.service                            enabled
pppd-dns.service                           enabled
repowerd.service                           enabled
resolvconf.service                         enabled
rsync.service                              enabled
rsyslog.service                            enabled
setvtrgb.service                           enabled
snapd.autoimport.service                   enabled
snapd.core-fixup.service                   enabled
snapd.service                              enabled
snapd.system-shutdown.service              enabled
ssh.service                                enabled
sshd.service                               enabled
syslog.service                             enabled
systemd-resolved.service                   enabled
systemd-timesyncd.service                  enabled
thermald.service                           enabled
ufw.service                                enabled
unattended-upgrades.service                enabled
ureadahead.service                         enabled
vboxautostart-service.service              enabled
vboxballoonctrl-service.service            enabled
vboxdrv.service                            enabled
vboxweb-service.service                    enabled
acpid.socket                               enabled
apport-forward.socket                      enabled
avahi-daemon.socket                        enabled
cups.socket                                enabled
snapd.socket                               enabled
uuidd.socket                               enabled
remote-fs.target                           enabled
apt-daily.timer                            enabled
motd-news.timer                            enabled
snapd.refresh.timer                        enabled

[download]

Hope this helps, BR.

Seeking for Perl wisdom...on the process of learning...not there...yet!

In reply to Re: Open Filehandle once (updated) by thanos1983
in thread Open Filehandle once by Dunkellbusch

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