[systemd-devel] What is the best way to run a shell script through 'ExecStart'

[Reindl Harald]

Am 30.09.2013 15:31, schrieb Tom Gundersen:
> On Mon, Sep 30, 2013 at 3:25 PM, Muhammad Shakeel
> <muhammad_shakeel at mentor.com> wrote:
>> I have been trying to convert a LSB initscript of a package into
>> corresponding systemd service fyile. Most init scripts are simple and
>> translating them into systemd unit files is non-trivial. In this case it is
>> a relatively long script involving some loops.
>>
>> 1) Should I write a script file separately and then call it through
>> 'ExecStart'?
>> or
>> 2) It would be good (and do-able) idea to fit whole script inside
>> ExecStart=/bin/sh -c " <script>"? (If yes, I would prefer it as it will free
>> me from hassle of maintaining two files)
> 
> If you need something non-trivial (such as loops or a script over more
> than a couple of lines), then I suggest keeping it in a separate file.
> Systemd service files intentionally do not support loops (or other
> control structures)

i tend to use PHP for most things because re-use of internal libraries
and a simple endless loop with "type=simple" does it's job

#!/usr/bin/php
while(1 == 1)
{

}
_______________________________________________

cat /etc/systemd/system/monitor-dbmail-imapd.service
[Unit]
Description=monitor dbmail-imapd
After=dbmail-imapd.service

[Service]
Type=simple
ExecStart=/usr/local/bin/check-dbmail-service.php 143 dbmail-imapd
Restart=always
RestartSec=1
TimeoutSec=1
Nice=19
IOSchedulingClass=3
User=dbmail
Group=dbmail
PrivateTmp=true
NoNewPrivileges=yes
CapabilityBoundingSet=CAP_KILL
ReadOnlyDirectories=/etc
ReadOnlyDirectories=/usr
ReadOnlyDirectories=/proc
ReadOnlyDirectories=/sys
InaccessibleDirectories=/boot
InaccessibleDirectories=/home
InaccessibleDirectories=/var/lib/rpm
InaccessibleDirectories=/var/lib/yum
InaccessibleDirectories=/var/spool

[Install]
WantedBy=multi-user.target
_______________________________________________

cat /usr/local/bin/check-dbmail-service.php
#!/usr/bin/php
<?php
 /** make sure we are running as shell-script */
 if(PHP_SAPI != 'cli')
 {
  exit('FORBIDDEN');
 }

 /** verify that port and binary-name are given */
 if(empty($_SERVER['argv'][1]) || empty($_SERVER['argv'][2]))
 {
  exit('USAGE: check-dbmail-service <port> <process-name>' . "\n");
 }

 /** service loop */
 while(1 == 1)
 {
  if(!check_service())
  {
   sleep(5);
   if(!check_service())
   {
    passthru('/usr/bin/killall -s SIGTERM ' . escapeshellarg($_SERVER['argv'][2]));
    usleep(750000);
    passthru('/usr/bin/killall -s SIGKILL ' . escapeshellarg($_SERVER['argv'][2]));
   }
  }
  sleep(30);
 }

 /**
  * check if service is available and responds
  *
  * @access public
  * @return boolean
 */
 function check_service()
 {
  $errno  = 0;
  $errstr = '';
  $fp = @fsockopen('tcp://127.0.0.1', $_SERVER['argv'][1], $errno, $errstr, 5);
  if($fp)
  {
   $response = @fgets($fp, 128);
   @fclose($fp);
   if(!empty($response))
   {
    return true;
   }
   else
   {
    return false;
   }
  }
  else
  {
   return false;
  }
 }
?>

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