10 More Discussions You Might Find Interesting
1. UNIX for Advanced & Expert Users
Dear members, moderators and others.
While working on <insert project>, a need has surfaced to watch a directory, and when a file comes, to do appropriate action.
So, i started writing some shell code, aware of linux inotify-tools package with inotifywait.
Also, i'm seeing a lot of similar... (1 Reply)
Discussion started by: Peasant
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2. SuSE
SUSE Linux 11 and 10 SP3.
I am trying to capture some of my activities in SYSLOG file, /var/log/messages.
To do this I created and dropped some test files and directories and users. But these activities are not captured in /var/log/messages. What should I do to make these activities... (7 Replies)
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3. UNIX for Advanced & Expert Users
Hello All,
I have below file system IN_CLOSE_WRITE event defined in my incrontab file, however it looks like the events kick off earlier even before the file transmission is complete and kicks off the shell script with partial file (file.xml.filepart) and causing issues. Is there any way i can... (4 Replies)
Discussion started by: Ariean
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4. UNIX for Advanced & Expert Users
ofIn a big Unix environment you likely install cron jobs like this on a thousand systems:
39 15 * * * { /usr/local/monitoring/sendstats ; } >/dev/null 2>&1If all the system clocks are synchronized (usually via NTP), these jobs run *exactly* at the same time.
If the cron job accesses a shared... (2 Replies)
Discussion started by: MadeInGermany
2 Replies
5. UNIX for Advanced & Expert Users
A well established form of application cron jobs look like this:
39 15 * * * && /usr/local/monitoring/oracle/check_dbs.sh >/dev/null 2>&1The repetition makes it a long line, hard to read, hard to maintain.
I suggest the following instead:
39 15 * * * { /usr/local/monitoring/oracle/check_dbs.sh... (1 Reply)
Discussion started by: MadeInGermany
1 Replies
6. Solaris
Greetings to all.
I need help from the experts. I have been given a FTP server script that runs all day, looking for files that are FTP'd to our machines. Its hoaky I know, but there are times that files are sent but somehow get lost. Is there a logfile I can view to see when files are received?
... (1 Reply)
Discussion started by: Harleyrci
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7. Shell Programming and Scripting
I need my for loop to do 2 things at a time. I have a script where I move the old files into archive directory and then i want to compress them. Presently I am using 2 for loops for it. How can i do it in 1 for loop.
Code:
after this i am compresing them in another for loop: (3 Replies)
Discussion started by: dsravan
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8. Shell Programming and Scripting
hi,
i need help writing shell scripts to define patterns of user activities on our apache.
i thought about going through logfiles and other places where user activities are stored and use that data to define patterns of action. i want these patterns to be visualized then.
now my... (3 Replies)
Discussion started by: rocketkids
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9. UNIX for Advanced & Expert Users
Hi!! Experts,
I have a typical scenario here in which several users have access to a particular login .. say "build".
None of the users know the passwd for this login.
The name of some of the user have been to .rhosts file.
The users can connect only by doing a rlogin to this id and then... (4 Replies)
Discussion started by: jyotipg
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10. UNIX for Advanced & Expert Users
I am responsible for administering 6 Tru64UX servers.
I need to keep an eye on all the commands executed by all the users.
Is there a way where I can save the commands executed in a seperate folder and then keep checking the list every now and then.
How can do it ? (5 Replies)
Discussion started by: shauche
5 Replies
CRON(8) System Administration CRON(8)
NAME
crond - daemon to execute scheduled commands
SYNOPSIS
crond [-c | -h | -i | -n | -p | -P | -s | -m<mailcommand>]
crond -x [ext,sch,proc,pars,load,misc,test,bit]
DESCRIPTION
Cron is started from /etc/rc.d/init.d or /etc/init.d when classical sysvinit scripts are used. In case systemd is enabled, then unit file
is installed into /lib/systemd/system/crond.service and daemon is started by systemctl start crond.service command. It returns immediately,
thus, there is no need to need to start it with the '&' parameter.
Cron searches /var/spool/cron for crontab files which are named after accounts in /etc/passwd; The found crontabs are loaded into the mem-
ory. Cron also searches for /etc/anacrontab and any files in the /etc/cron.d directory, which have a different format (see crontab(5)).
Cron examines all stored crontabs and checks each job to see if it needs to be run in the current minute. When executing commands, any
output is mailed to the owner of the crontab (or to the user specified in the MAILTO environment variable in the crontab, if such exists).
Any job output can also be sent to syslog by using the -s option.
There are two ways how changes in crontables are checked. The first method is checking the modtime of a file. The second method is using
the inotify support. Using of inotify is logged in the /var/log/cron log after the daemon is started. The inotify support checks for
changes in all crontables and accesses the hard disk only when a change is detected.
When using the modtime option, Cron checks its crontables' modtimes every minute to check for any changes and reloads the crontables which
have changed. There is no need to restart Cron after some of the crontables were modified. The modtime option is also used when inotify
can not be initialized.
Cron checks these files and directories:
/etc/crontab
system crontab. Nowadays the file is empty by default. Originally it was usually used to run daily, weekly, monthly jobs. By
default these jobs are now run through anacron which reads /etc/anacrontab configuration file. See anacrontab(5) for more details.
/etc/cron.d/
directory that contains system cronjobs stored for different users.
/var/spool/cron
directory that contains user crontables created by the crontab command.
Note that the crontab(1) command updates the modtime of the spool directory whenever it changes a crontab.
Daylight Saving Time and other time changes
Local time changes of less than three hours, such as those caused by the Daylight Saving Time changes, are handled in a special way. This
only applies to jobs that run at a specific time and jobs that run with a granularity greater than one hour. Jobs that run more frequently
are scheduled normally.
If time was adjusted one hour forward, those jobs that would have run in the interval that has been skipped will be run immediately. Con-
versely, if time was adjusted backward, running the same job twice is avoided.
Time changes of more than 3 hours are considered to be corrections to the clock or the timezone, and the new time is used immediately.
It is possible to use different time zones for crontables. See crontab(5) for more information.
PAM Access Control
Cron supports access control with PAM if the system has PAM installed. For more information, see pam(8). A PAM configuration file for
crond is installed in /etc/pam.d/crond. The daemon loads the PAM environment from the pam_env module. This can be overridden by defining
specific settings in the appropriate crontab file.
OPTIONS
-h Prints a help message and exits.
-i Disables inotify support.
-m This option allows you to specify a shell command to use for sending Cron mail output instead of using sendmail(8) This command must
accept a fully formatted mail message (with headers) on standard input and send it as a mail message to the recipients specified in
the mail headers. Specifying the string off (i.e., crond -m off) will disable the sending of mail.
-n Tells the daemon to run in the foreground. This can be useful when starting it out of init. With this option is needed to change
pam setting. /etc/pam.d/crond must not enable pam_loginuid.so module.
-p Allows Cron to accept any user set crontables.
-P Don't set PATH. PATH is instead inherited from the environment.
-c This option enables clustering support, as described below.
-s This option will direct Cron to send the job output to the system log using syslog(3). This is useful if your system does not have
sendmail(8), installed or if mail is disabled.
-x This option allows you to set debug flags.
SIGNALS
When the SIGHUP is received, the Cron daemon will close and reopen its log file. This proves to be useful in scripts which rotate and age
log files. Naturally, this is not relevant if Cron was built to use syslog(3).
CLUSTERING SUPPORT
In this version of Cron it is possible to use a network-mounted shared /var/spool/cron across a cluster of hosts and specify that only one
of the hosts should run the crontab jobs in this directory at any one time. This is done by starting Cron with the -c option, and have the
/var/spool/cron/.cron.hostname file contain just one line, which represents the hostname of whichever host in the cluster should run the
jobs. If this file does not exist, or the hostname in it does not match that returned by gethostname(2), then all crontab files in this
directory are ignored. This has no effect on cron jobs specified in the /etc/crontab file or on files in the /etc/cron.d directory. These
files are always run and considered host-specific.
Rather than editing /var/spool/cron/.cron.hostname directly, use the -n option of crontab(1) to specify the host.
You should ensure that all hosts in a cluster, and the file server from which they mount the shared crontab directory, have closely syn-
chronised clocks, e.g., using ntpd(8), otherwise the results will be very unpredictable.
Using cluster sharing automatically disables inotify support, because inotify cannot be relied on with network-mounted shared file systems.
CAVEATS
All crontab files have to be regular files or symlinks to regular files, they must not be executable or writable for anyone else but the
owner. This requirement can be overridden by using the -p option on the crond command line. If inotify support is in use, changes in the
symlinked crontabs are not automatically noticed by the cron daemon. The cron daemon must receive a SIGHUP signal to reload the crontabs.
This is a limitation of the inotify API.
The syslog output will be used instead of mail, when sendmail is not installed.
SEE ALSO
crontab(1), crontab(5), inotify(7), pam(8)
AUTHOR
Paul Vixie <vixie@isc.org>
Marcela Malaova <mmaslano@redhat.com>
Colin Dean <colin@colin-dean.org>
cronie 2013-09-26 CRON(8)