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Full Discussion: [PHP] endless loop mimics a cron. Make sure only one instance is running
Top Forums Shell Programming and Scripting [PHP] endless loop mimics a cron. Make sure only one instance is running Post 302271246 by jjshell on Wednesday 24th of December 2008 11:00:53 AM
Old 12-24-2008
Thank you very much. Smilie

I'm very new to this, so please excuse a fire of questions.

Quote:
Originally Posted by tderscheid
Your script has a log file, right? Have it write to the log file after it's finished doing whatever it does, and before it sleeps:

Code:
echo 'date' Done - going to sleep >> /tmp/script.sleep.log

I hadn't thought about a log file. But it makes sense. However, since the script executes itself every 30 seconds, 8 hours a day, 5 days a week, I guess I would only log failures (if not, I would end up with a huge log file). What would be your approach?

Quote:
Originally Posted by tderscheid
You can then tail -f the log and watch it roll, check the timestamp on it to see when last updated, figure out when it failed, etc.
The tail command reads and print the final lines of an input. So I would basically read the log file, correct?

Quote:
Originally Posted by tderscheid
I usually count processes by doing something like this:

Code:
ps -aef | grep -v grep | grep very_unique_scriptname | wc -l | bc

Very interesting, even though it will take some serious time for a command newbie like me to translate it into an understandable sentence Smilie
 

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LEARN ABOUT OSF1

log

log(8)							      System Manager's Manual							    log(8)

NAME

       log - Records input and output from a program

SYNOPSIS

       /usr/sbin/log <logfile> <command>

OPERANDS

       The file in which to record the interaction being logged.  The command to execute.

DESCRIPTION

       The  log  program  runs <command> and logs the input to and output from <command> to the <logfile> file.  Input and output are logged until
       <command> exits, the log program exits, and the exit status of <command> is returned.

       The log program is used by the system  installation  procedure  and  the  it(8)	command  to  create  the  /var/adm/smlogs/install.log  and
       /var/adm/smlogs/it.log installation log files.

RESTRICTIONS

       Because	the  log  program is used in the installation standalone environment, program size was the greatest concern in its implementation.
       The log program does not search for the PATH variable to locate <command> and error messages are terse.

       The log program causes <command> to take standard input from and write standard output and standard error to  UNIX  pipes.   Some  commands
       will  not  be able to operate in this environment; therefore, it is suggested that you use the script(1) command instead.  UNIX shells will
       not issue prompts when run from log unless the shell is started with an explicit interactive switch (-i for most shells).  For example, log
       foo.tmp /sbin/sh -i

       In the previous example, foo.tmp is the name of <logfile>.

       The  log  program  intercepts  end-of-file (usually Ctrl/d).  Therefore programs which normally receive end-of-file as an exit command must
       exit by some other means.

ERRORS

       Log open error

   Explanation:
       The log program was unable to open <logfile>. Verify that the directory exists and that ownerships and permissions are set correctly.

       Exec Error

   Explanation:
       The log program was unable to execute <command>. Verify that you specified a full pathname for <command> and  that  <command>  is  an  exe-
       cutable file.

       Fork Error

   Explanation:
       The log program was unable to create one of the processes it requires to log data.

SEE ALSO

       Commands: it(8), script(1)

																	    log(8)
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