my_cron-file works when it's created directly in /etc/cron.d/:
sudo nano /etc/cron.d/my_cron
# Add content:
* * * * * username /path/to/python /path/to/file 2>/path/to/log
But it doesn't work when I copy/move it to the directory:
sudo cp ./my_cron /etc/cron.d/my_cron
ls -l /etc/cron.d outputs the same permissions both times: -rw-r--r--. The files are owned by root.
The only reason I could imagine at the moment is that I've to refresh/activate something after copying, which happens automatically on creation.
Tested on Ubuntu and Raspbian.
Any idea? Thanks!
Older cron daemons used to examine /etc/cron.d for updated content only when they saw that the last-modified timestamp of that directory, or of the /etc/crontab file, had changed since the last time cron scanned it. Recent cron daemons also examine the timestamps of the individual files in /etc/cron.d but maybe you're dealing with an old one here.
If you have an old cron, then if you copied a brand new file into /etc/cron.d then the directory's timestamp should change and cron should notice the new file.
However, if your cp was merely overwriting an existing file then that would not change the directory timestamp and cron would not pick up the new file content.
Editing a file in-place in /etc/cron.d would not necessarily update the directory timestamp, but some editors (certainly vi, unless you've configured it otherwise) will create temporary working files and perhaps a backup file in the directory where the file being edited lives. The creation and deletion of those other files will cause the directory timestamp to be updated, and that will cause cron to put the edited file into effect. This could explain why editing behaves differently for you than cp'ing does.
To force a timestamp to be updated you could do something like sudo touch /etc/crontab or create and immediately remove a scratch file (or a directory) in /etc/cron.d after you've cp'ed or rm'ed a file in there. Obviously touch is easier. If you want to go the create+delete route then mktemp would be a good tool to use for that, in order to avoid clobbering someone else's legitimate file.
If you were really paranoid, you'd wait at least a second between making file changes and then doing whatever you choose to do to force a timestamp update. That should avoid the situation where a cron rescan, your file updates, and your touch or scratch create+delete could all happen within the granularity of the timestamp.
If you want to see what your cron is actually doing, you can sudo strace -p <pid-of-cron>. Mostly it sleeps for a minute at a time, but you'll see it stat some files and directories (including /etc/crontab and /etc/cron.d) each time it wakes up. And of course if it decides that it needs to run a job, you'll see that activity too.
Related
I want to empty (not delete) log files daily at a particular time. something like
echo "" > /home/user/dir/log/*.log
but it returns
-bash: /home/user/dir/log/*.log: ambiguous redirect
is there any way to achieve this?
You can't redirect to more than one file, but you can tee to multiple files.
tee /home/user/dir/log/*.log </dev/null
The redirect from /dev/null also avoids writing an empty line to the beginning of each file, which was another bug in your attempt. (Perhaps specify nullglob to avoid creating a file with the name *.log if the wildcard doesn't match any existing files, though.)
However, a much better solution is probably to use the utility logrotate which is installed out of the box on every Debian (and thus also Ubuntu, Mint, etc) installation. It runs nightly by default, and can be configured by dropping a file in its configuration directory. It lets you compress the previous version of a log file instead of just overwrite, and takes care to preserve ownership and permissions etc.
I'm trying to add a daily cron job to backup a database. I'm able to do it manually by running sh /path/to/file/backup.sh but when I place the file in the cron.daily directory, it doesn't run daily. To try and diagnose it, I created a test file in cron.daily called test just to see if it would run. When I ran run-parts --test /etc/cron.daily, I got the output
/etc/cron.daily/apache2
/etc/cron.daily/apt
/etc/cron.daily/bsdmainutils
/etc/cron.daily/dpkg
/etc/cron.daily/etckeeper
/etc/cron.daily/logrotate, etc.
So then I tried copying the content of logrotate to a new file, atest, then ran run-parts again but with the same results.
atest:
#!/bin/sh
test -x /usr/sbin/logrotate || exit 0
/usr/sbin/logrotate /etc/logrotate.conf
Is there something special I need to do to get cron to recognize a newly added task in cron.daily?
This isn't unique to cron.daily, I've tried monthy, weekly, and hourly as well with the same results. I've also tried restarting cron without success. I'm running this on Debian 7.2.
There are a couple of things that can keep files within your /etc/cron* directories from running (e.g. /etc/cron.daily):
Permissions. Make sure the permissions of the files are 0644.
The filename must meet certain conditions. From the documentation: "...they must be entirely made up of letters, digits and can only contain the special signs, underscores ('_') and hyphens ('-'). Any file that does not conform to these requirements will not be executed by run-parts.
I've got a CentOS installation with a busy webserver.
I need to aquire stats from the log files and keep the old ones, ordered by date.
Every 30th second, the current logfile should be closed and processed (analysing entries and storing them into a database). Since this generates a lot of logfiles, I want to group them into directories, named by date.
At the moment, I have two files; rotation.conf and rotatenow.sh. The shell-file creates directories, based on YmdHMS.
After that, I run the command "logrotate ./rotation.conf -v --force" in order to invoke the proces, but how do I make the config-file put the log into the newly generated directory? Can the whole thing be done inside the config-file?
now="$(date)"
now="$(date +'%Y-%m-%d-%H:%M:%S')"
foldernavn="/var/www/html/stats/logs/nmdstats/closed/$now"
mkdir $foldernavn
logrotate ./nmdhosting.conf -v --force
At the moment, the config-file looks like this:
/var/www/html/stats/logs/nmdhosting/access_log {
ifempty
missingok
(I am stuck)
(do some post-processing - run a Perl-script)
}
Any ideas would be deeply appreciated.
Update: I tried a different approach, adding this to the httpd.conf:
TransferLog "|usr/sbin/rotatelogs /var/www/html/stats/logs/nmdstats/closed/activity_log.%Y%m%d%H%M%S 30".
It works, but apparently, it can't run a pre/post processing script when using this method. This is essential in order to update the database. I could perhaps run a shell/Perl-script using a cronjob, but I don't trust that method. The search goes on...
update 2:
I've also tested cronolog but the - for my project - required functionalities haven't been implemented yet, but are on the to-do. Since the latest version is from 2002, I'm not going to wait around for it to happen :)
However, I was unaware of the inotify-tools, so I managed to set up a listener:
srcdir="/var/www/html/stats/logs/nmdstats/history/"
inotifywait -m -e create $srcdir |
while read filename eventlist eventfile
do
echo "This logfile has just been closed: $eventfile"
done
I think, I can handle it from here. Thank you, John
No need for cron: if you use the TranserLog httpd.conf option to create a new log file every 30 seconds, you can run a post-processing daemon which watches the output directory with inotifywait (or Python's pyinotify, etc.). See here: inotify and bash - this will let you get notified by the OS very soon after a new file is created etc.
I have a server at hostname.com/files. Whenever a file has been uploaded I want to download it.
I was thinking of creating a script that constantly checked the files directory. It would check the timestamp of the files on the server and download them based on that.
Is it possible to check the files timestamp using a bash script? Are there better ways of doing this?
I could just download all the files in the server every 1 hour. Would it therefore be better to use a cron job?
If you have a regular interval at which you'd like to update your files, yes, a cron job is probably your best bet. Just write a script that does the checking and run that at an hourly interval.
As #Barmar commented above, rsync could be another option. Put something like this in the crontab and you should be set:
# min hour day month day-of-week user command
17 * * * * user rsync -av http://hostname.com/ >> rsync.log
would grab files from the server in that location and append the details to rsync.log on the 17th minute of every hour. Right now, though, I can't seem to get rsync to get files from a webserver.
Another option using wget is:
wget -Nrb -np -o wget.log http://hostname.com/
where -N re-downloads only files newer than the timestamp on the local version, -b sends
the process to the background, -r recurses into directories and -o specifies a log file. This works from an arbitrary web server. -np makes sure it doesn't go up into a parent directory, effectively spidering the entire server's content.
More details, as usual, will be in the man pages of rsync or wget.
I have a bash script which creates a mysqldump backup every hour in a certain directory.
The filenames of the backup files include the date and hour as per the following schema:
backupfile_<day>-<month>-<year>_<hour>.sql.gz
and to clarify here are some example filenames:
backupfile_30-05-2012_0800.sql.gz
backupfile_01-06-2012_0100.sql.gz
backupfile_05-06-2012_1500.sql.gz
Would someone help me with creating a script that will loop through all files in the directory and then delete files LEAVING the following:
Keep alternate hour backups older than a day
Keep twice daily backups older than a week
Keep once daily backups older than a month.
I have the following beginnings of the script:
#!/bin/bash
cd /backup_dir
for file in *
do
# do the magic to find out if this files time is up (i.e. needs to be deleted)
# delete the file
done
I have seen many fancy scripts like this for taking scheduled backups and wonder why folks don't make a use of logroate utility available on most of *nix distros available today support following options of your interest:
compress
Old versions of log files are compressed with gzip by default.
dateext
Archive old versions of log files adding a daily extension like YYYYMMDD instead
of simply adding a number.
olddir directory
Logs are moved into directory for rotation. The directory must be on the same
physical device as the log file being rotated, and is assumed to be relative to
the directory holding the log file unless an absolute path name is specified.
When this option is used all old versions of the log end up in directory. This
option may be overriden by the noolddir option.
notifempty
Do not rotate the log if it is empty (this overrides the ifempty option).
postrotate/endscript
The lines between postrotate and endscript (both of which must appear on lines by
themselves) are executed after the log file is rotated. These directives may
only appear inside of a log file definition. See prerotate as well.
You can parse your timestamps by iterating over filenames, or you can use the -cmin flag in the find command (see man 1 find for details).