Commands matching cron

I don't know if the --spider option works to execute a script, but it might be worth trying. Note that the Drupal project uses the following in a cron job.

The output is sent to standard out so it can be logged by cron.

I have a remote php file that I want to run once an hour. I set up cron to run this wget. I don't really care about what's in the file though, I don't want to save the results, so I run the -O and send it to /dev/null

You can view the man pages from section five by passing the section number as an argument to the man command

Instead of using:

0,15,30,45 * * * * /path/to/command

This is helpful for shell scripts, I use it in my custom php install script to schedule to delete the build files in 3 hours, as the php install script is completely automated and is made to run slow.

Does require at, which some environments without crontab still do have.

You can add as many commands to the at you want. Here's how I delete them in case the script gets killed. (trapped)

atq |awk '{print $1}'|xargs -iJ atrm J &>/dev/null

this lets you edit a crontab file (which may be used as a backup as well) and insert this into your crontab. this way is especially handy, when multiple users are working on one account (e.g. root)

This command finds the 5 (-n5) most frequently updated logs in /var/log, and then does a multifile tail follow of those log files.

Alternately, you can do this to follow a specific list of log files:

sudo tail -n0 -f /var/log/{messages,secure,cron,cups/error_log}

This is great if you are behind a router that does not support dynamic dns updates!

Example: AT&T u-verse gateway...

Put this in a script and run it as a cron job.

additionally use "find /etc/cron*" for cronscripts

With this you can unlock your KDE4 session via SSH, via mobile phone SSH or e. g. scheduled task in crontab (without asking password). Useful when you need to grant somebody access to your locked profile remotely.

Create an alias (e. g. as "unlock") and use with remote KDE4 lock.

This works only on KDE4 boxes because KDE 3 is using utility with another name.

Tested on Kubuntu 8.10.

This is useful if you have need to do port forwarding and your router doesn't assign static IPs, you can add it to a script in a cron job that checks if you IP as recently changed or with a trigger script.

This was tested on Mac OSX.

I find it ugly & sexy at the same time isn't it ?

This command will tell lynx to read keystrokes from the specified file - which can be used in a cronjob to auto-login on websites that give you points for logging in once a day *cough cough* (which is why I used -accept_all_cookies).

For creating your keystroke file, use:

The large context number (-C 1000) is a bit of a hack, but in most of my use cases, it makes sure I'll see the whole log output.

Useful for cron jobs -- all output will be logged but only errors will cause email to be sent. NB the order of "2>&1" and ">> logfile" is important, it doesn't work if you reverse them (everything goes to the logfile, nothing left for tee).

or replace "espeak" with "festival --tts" if you like festival better

when your buddy leaves his computer unlocked use "crontab" or "at" to play at some time that would be most embarassing (during his next sales presentation)

of course you can exclude the "-o" for non offensive fortunes, or if you don't have offensive fortunes installed

This is handy to just shove into a daily cron entry. If you do use cron, make sure to escape the %d with \%d or it will fail.

I have this on a daily cronjob to backup the commandlinefu.com database from NearlyFreeSpeech.net (awesome hosts by the way) to my local drive. Note that (on my Ubuntu system at least) you need to escape the % signs on the crontab.

This comes in handy if you have daemons/programs that have potential issues and stop/disappear, etc., can be run in cron to ensure that a program remains up no matter what. Be advised though, if a program did core out, you'd likely want to know why (gdb) so use with caution on production machines.

This command specifies the size in Kilobytes using 'k' in the -size +(N)k option. The plus sign says greater than. -exec [cmd] {} \; invokes ls -l command on each file and awk strips off the values of the 5th (size) and the 9th (filename) column from the ls -l output to display. Sort is done in reversed order (descending) numerically using sort -rn options.

A cron job could be run to execute a script like this and alert the users if a dir has files exceeding certain size, and provide file details as well.

I know its not much but is very useful in time consuming scripts (cron, rc.d, etc).

Useful for a cron job that runs nightly, gzipping or alternatively deleting files from a specific directory that are older than 10 days (in this case)

Original author unknown (I believe off of a wifi hacking forum).

Used in conjuction with ifconfig and cron.. can be handy (especially spoofing AP's)

great for outputting tweets from cron jobs and batch scripts