03-08-2012
In the semaphore method, the script first checks for the presence of a semaphore file and exits if the file is present. If the file is not present the script immediately creates the semaphore file and subseqently deletes the semaphore file on exit.
Some people call this an interlock file (or even a mutex).
This semaphore file also gives you a reference for when the script started so a monitoring process could detect an overrunning process.
10 More Discussions You Might Find Interesting
1. UNIX for Advanced & Expert Users
I have written a shell script and when i run it from shell prompt it runs fine but in the cron it only runs partially.
That means cron is working fine.
there is a command which i am using in the script which doesn't run at all.
That comman uses different user privileges like ptadmin
i am not... (4 Replies)
Discussion started by: ajnabi
4 Replies
2. UNIX for Dummies Questions & Answers
I am trying to schedule a new job but I get
# cron
# ! cron is already running Mon Jul 11 08:28:51 WAT 2005
! ******* CRON ABORTED ******** Mon Jul 11 08:28:51 WAT 2005
I tried the -l and -e switches but I get the same message
I am using HP-UX
Thanks. (3 Replies)
Discussion started by: GNMIKE
3 Replies
3. HP-UX
Hi,
I have a cron schedule like this
04,16,28,40,52 * * * * /nag/startProcessABatch (unix script)
i want to add new lines in this file (like Logging), i just copy this file into a /tmp folder (for backup copy), and i have edited this file (added few lines of code for logging).
... (1 Reply)
Discussion started by: nag_sundaram
1 Replies
4. UNIX for Dummies Questions & Answers
I would like to add a job using cron. I have following questions
- cron jobs are launched using what login-id
e.g. is the script launced using my login-id
- In which directory would the cron jobs be launched ?
- where do the environment variables required in the script being lauched come... (3 Replies)
Discussion started by: sharanbr
3 Replies
5. Shell Programming and Scripting
i have a simple script that ftp a file out, manually running it works fine.
#!/bin/sh
ftp 152.226.69.48 << cmd
bin
get applicant_vw.txt
quit
cmd
but when I cron it,
14 9 * * * /opt/home/XXX/XXX/dailyjob.sh > /opt/home/XXX/XXX/cronlog.txt
seems that it was executed because i can... (2 Replies)
Discussion started by: beisaikong
2 Replies
6. UNIX for Advanced & Expert Users
Hello All,
I have installed a few crons on a machine. But for some reason the crons just don't run. I have checked the permissions on the files and also restarted the cron daemon. But it doesn't seem ti help. Can anyone suggest any other things I can do to get it running again?
Regards,... (6 Replies)
Discussion started by: garric
6 Replies
7. Solaris
I need to run a script (from cron) that runs a second script.
What worries me is that second script, when run from bash, upon finishing doesn't return to bash unless I press the 'Enter' key.
I presume that's because last command in that script ends with &
Could that be a problem for cron?... (2 Replies)
Discussion started by: orange47
2 Replies
8. UNIX for Advanced & Expert Users
Hi all,
I have a solris 10 machine and i am facing some strange issues.
My sys user cron is not executing.
Can any one help on this issue?
root@antsdp1b>svcs -a|grep -i cron
online 1:08:55 svc:/system/cron:default
root@antsdp1b>
the cron process is also running. but whatever i... (5 Replies)
Discussion started by: vivek.goel.piet
5 Replies
9. Solaris
Hi ,
I have removed a cron for particular user , but cron job seems to be running even after the cron entry is removed. The purpose of the cron was to sendmail to user ( it uses mailx utility )
I have restarted cron and sendmail service still user is getting mail alerts from the cron job. And... (4 Replies)
Discussion started by: chidori
4 Replies
10. Shell Programming and Scripting
Hi All,
I have a script which is running fine while triggered manually, However if I placed
in crontab it throwing an error.
#!/usr/bin/ksh
set -vx
lc=1
st_date=$(`date "+%Y%m%d"`)
LOGFILE=/home/transfer.log.$st_date
file="/home/OM_WF.log.$st_date"
Manual run -
lc=1
+ lc=1... (4 Replies)
Discussion started by: nag_sathi
4 Replies
LEARN ABOUT HPUX
sem_unlink
sem_unlink(2) System Calls Manual sem_unlink(2)
NAME
sem_unlink - unlink a named POSIX semaphore
SYNOPSIS
DESCRIPTION
is used to unlink named semaphores. A successful call to marks the semaphore, specified by name, for removal. Calling does not affect
processes, including the calling process, which currently have a descriptor, obtained from a call to Named semaphores are uniquely identi-
fied by character strings. All character string names will be pre-processed to ensure variations of a pathname resolve to the same sema-
phore name. If the semaphore is successfully marked for removal by a call to the semaphore will be removed when all processes remove their
descriptors to the specified semaphore by calling Subsequent calls to using the string name will refer to a new semaphore.
To use this function, link in the realtime library by specifying on the compiler or linker command line.
EXAMPLES
The following call to will remove the named semaphore named by the string name. If the semaphore is currently referenced by one or more
processes, the semaphore will be marked for removal and removed when there are no more processes referencing it.
RETURN VALUE
If the semaphore was unlinked successfully, returns 0.
If the semaphore could not be unlinked, the call returns -1 and sets to indicate the error.
ERRORS
fails and does not perform the requested operation if any of the following conditions are encountered:
[EACCES] The named semaphore exists and the process does not have the permissions to unlink the semaphore.
[ENAMETOOLONG] The name string is longer than
[ENOENT] The flag is not set in oflag (see sem_open(2)) and the named semaphore does not exist.
SEE ALSO
sem_close(2), sem_open(2), privileges(5), <semaphore.h>.
STANDARDS CONFORMANCE
sem_unlink(2)