crontab -e only creates temporary files in tmp. it never runs

[finny388]

crontab -e

pulls up my personal crontab (that I orig created with crontab -e)
I run SearchMonkey and it finds 3 instances of files named crontab in the following locations:
1. /tmp/crontab.YeXHKM (this is my crontab)
2. /etc (this looks like an official crontab)
3. /usr/bin (open in Kate and it is illegible characters (not a text file))
back to terminal I exit pico and successfully save changes
Rerun SearchMonkey and now the /tmp entry is gone.

So nowhere in this desktop search (recursively going through root folder) does my crontab show up yet if I go back to terminal and try again it pops up again (and /tmp is populated again)).

entries in personal tab don't run. I also tried adding a line to the /etc file. neither work and I can't find a log file

here are the two file's content:
/tmp/crontab.dlkdsjf

55 * * * * root echo "hello"

/etc

# /etc/crontab: system-wide crontab
# Unlike any other crontab you don't have to run the `crontab'
# command to install the new version when you edit this file
# and files in /etc/cron.d. These files also have username fields,
# that none of the other crontabs do.

SHELL=/bin/sh
PATH=/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin

# m h dom mon dow user	command
17 *	* * *	root  cd / && run-parts --report /etc/cron.hourly
25 6	* * *	root	test -x /usr/sbin/anacron || ( cd / && run-parts --report /etc/cron.daily )
47 6	* * 7	root	test -x /usr/sbin/anacron || ( cd / && run-parts --report /etc/cron.weekly )
52 6	1 * *	root	test -x /usr/sbin/anacron || ( cd / && run-parts --report /etc/cron.monthly )
55 * * * * root echo "hello"
#

confused

[Rog131]

Re: crontab -e only creates temporary files in tmp. it never runs

CLI

> CronHowto


With the KDE (gui)

Package: kcron

program scheduler for KDE 4
KCron is a system settings module for scheduling programs to run at specific
intervals using cron, the UNIX scheduling service.

K > System Settings > Advanced > Task Scheduler


Earlier:
> Topic: How to create a system cron in Task Scheduler?
> Topic: kcron confusion - SOLVED


Crontab location

/var/spool/cron/crontabs/$USER

> Intro to cron:

...The main config file is normally /etc/crontab...

Multiuser cron

...The crontab file is often stored in /var/spool/cron/crontabs/<user> (Unix/Slackware/*BSD),
/var/spool/cron/<user> (RedHat) or /var/cron/tabs/<user> (SuSE),
but might be kept elsewhere depending on what Un*x flavor you're running...

sudo ls -l /var/spool/cron/crontabs/

-rw------- 1 rog crontab 341 2010-04-08 23:24 rog
-rw------- 1 root crontab 273 2010-04-02 14:28 root

Output to the display

...
here are the two file's content:
/tmp/crontab.dlkdsjf

55 * * * * root echo "hello"
...

The Cron needs to know to where (display) and with what application (konsole, kdialog, ...)

Exaple with the kdialog /1/. Adding 5 sec popup (using the KCron):

kdialog --display :0 --passivepopup hello 5

Crontab is telling

crontab -l

#No comment
25 23 8 4 * kdialog --display :0 --passivepopup hello 5


# File generated by KCron the Thursday 08 April 2010 23:24.

With the cat:

sudo cat /var/spool/cron/crontabs/rog

# DO NOT EDIT THIS FILE - edit the master and reinstall.
# (/tmp/kde-rog/systemsettingsVY2911.tmp installed on Thu Apr 8 23:24:03 2010)
# (Cron version -- $Id: crontab.c,v 2.13 1994/01/17 03:20:37 vixie Exp $)
#No comment
25 23 8 4 * kdialog --display :0 --passivepopup hello 5


# File generated by KCron the Thursday 08 April 2010 23:24.

[img width=400 height=104]http://img196.imageshack.us/img196/7662/kdialog.png[/img]


/1/ kdialog --help

Usage: kdialog [Qt-options] [KDE-options] [options] [arg]

KDialog can be used to show nice dialog boxes from shell scripts

[finny388]

Re: crontab -e only creates temporary files in tmp. it never runs

Thank you Rog. That was a great reply with lots of info.

So the only thing wrong was my cron syntax.

I tested your dialoguebox command and it worked. (I always wanted to create my own notices)

2 more questions.

1. I installed kcron. But it did not show up in K Menu and I cannot find it. How do I run it?

2. I want ktorrent to run every night at 2am. What would the cron line look like for that?
I've tried
38 * * * * /usr/bin/ktorrent
and
38 * * * * ktorrent

[finny388]

Re: crontab -e only creates temporary files in tmp. it never runs

I found task scheduler in the System Settings/Advanced

But even there I could not get it to run ktorrent

[Rog131]

Re: crontab -e only creates temporary files in tmp. it never runs

I found task scheduler in the System Settings/Advanced

But even there I could not get it to run ktorrent

Try with the "--display :0"


Here:

/usr/bin/ktorrent --display :0

=>

crontab -l

#No comment
15 17 * * * /usr/bin/ktorrent --display :0


# File generated by KCron the Friday 09 April 2010 17:11.

and

[img width=400 height=260]http://img519.imageshack.us/img519/1929/ktorrrenttodisplay0.png[/img]

The Ktorrent was poping up 17.15


Note !
If the Ktorrent is closed from the system tray it will open to the system tray.

[finny388]

Re: crontab -e only creates temporary files in tmp. it never runs

Hello Rog,

That did work but terminal also comes up with this message:
-------------------------------------------------------------------------
End of script execution. Type Enter or Ctrl+C to exit.
-------------------------------------------------------------------------

Can that be prevented?
More importantly, where can I learn more about this? I googled ktorrent, bash, command line, parameters, terminal, and I could not find a reference to ktorrent's command line parameters anywhere.

thanks

[Rog131]

Re: crontab -e only creates temporary files in tmp. it never runs

A good place to start is Kubuntu Forums > Important Information > Documentation. There you can find > HOWTO find Kubuntu's manual / reference / guide / documentation / help.

And if you look closely you can see > The art of using manuals at my "signature".

ktorrent --help-all

Usage: ktorrent [Qt-options] [KDE-options] [Url]

Bittorrent client for KDE

<clip>
Qt options:
--display <displayname> Use the X-server display 'displayname'
<clip>

[finny388]

Re: crontab -e only creates temporary files in tmp. it never runs

Thanks again Rog, I read through the art of using manuals and the --help of ktorrent.

1. When you tested ktorrent with kcron, did the terminal show up like it did for me? (reading through all the help I don't see anything that will stop this.
2. --help doesn't say anything about ":0" as a parameter. What is this about?

[Rog131]

Re: crontab -e only creates temporary files in tmp. it never runs

1. When you tested ktorrent with kcron, did the terminal show up like it did for me? (reading through all the help I don't see anything that will stop this.

I don't have script problems.

Are you using scripts ?



More > KTorrent wiki

2. --help doesn't say anything about ":0" as a parameter. What is this about?

The Linux is using the X:

man X

NAME
X - a portable, network-transparent window system

SYNOPSIS
The X Window System is a network transparent window system which runs on a wide range of computing and graphics machines. It should be relatively straightforward to build the X.Org Foundation software distribution on most ANSI C and POSIX compliant systems. Commercial implementations are also available for a wide range of platforms...


DISPLAY NAMES
From the user's perspective, every X server has a display name of the form:

hostname:displaynumber.screennumber

+ lot of stuff

=> :0

[finny388]

Re: crontab -e only creates temporary files in tmp. it never runs

1.
I'm not using any scripts in Ktorrent. (didn't notice that sidebar until you posted)

But I have the same 3 items in the Scripts sidebar.

I am not using scripts anywhere that I know of.

2.
Are you saying I will find :0 in the man X text?
I tried but couldn't find any mention?
What does :0 do?

Thanks again!

[Snowhog]

Re: crontab -e only creates temporary files in tmp. it never runs

2.
Are you saying I will find :0 in the man X text?
I tried but couldn't find any mention?
What does :0 do?

Thanks again!

Yes, it's in the man X text:

DISPLAY NAMES
From the user's perspective, every X server has a display name of the form:

hostname:displaynumber.screennumber

This information is used by the application to determine how it should connect to the
server and which screen it should use by default (on displays with multiple monitors):

hostname
The hostname specifies the name of the machine to which the display is physi‐
cally connected. If the hostname is not given, the most efficient way of com‐
municating to a server on the same machine will be used.

displaynumber
The phrase "display" is usually used to refer to collection of monitors that
share a common keyboard and pointer (mouse, tablet, etc.). Most workstations
tend to only have one keyboard, and therefore, only one display. Larger,
multi-user systems, however, frequently have several displays so that more than
one person can be doing graphics work at once. To avoid confusion, each dis‐
play on a machine is assigned a display number (beginning at 0) when the X
server for that display is started. The display number must always be given in
a display name.

screennumber
Some displays share a single keyboard and pointer among two or more monitors.

[kubicle]

Re: crontab -e only creates temporary files in tmp. it never runs

2.
Are you saying I will find :0 in the man X text?
I tried but couldn't find any mention?
What does :0 do?

Snowhog already posted the information, but if you're wondering how it all fits together, I'll explain a bit further:

<clip>
Qt options:
--display <displayname> Use the X-server display 'displayname'
<clip>

As you can see, the '--display' option requires that you give an additional argument, 'displayname'. Because --display allows you to set the $DISPLAY variable for the program, it's natural that you also have to actually set a value for it ('--display' without 'displayname' wouldn't do anything).

hostname:displaynumber.screennumber

This is the syntax for 'displayname', but hostname and screennumber can be omitted (they default to 'localhost' and '.0'). ':0' is the same as ':0.0', for example, and means the "first screen of the first X session running on this machine"

Why do you need these displaynames?
You can run programs on multiple hosts (local or remote), a host can have more than one X session running, and every X session can have more than one screen, and the "displayname" allows you to distinguish between them. The $DISPLAY variable tells a graphical program where it should show it's window.

Why do you need to define the displayname for cron?
Normally (when running an X session) the $DISPLAY variable is set so the programs you start within the session know which display to start on (by default)...you can test this by starting konsole and running "echo $DISPLAY". (of course if you wish to start a program showing it's window on another host, another X session or another screen, you'll need to define displayname accordingly)

However, the $DISPLAY variable is usually set only within the X session, and cron (like ttys) does not run within the session (as a system service, it starts and runs independently from X sessions). So if you wish to run graphical programs with cron, you'll need to set the $DISPLAY for the program.

[Snowhog]

Re: crontab -e only creates temporary files in tmp. it never runs

Nicely explained.

[finny388]

Re: crontab -e only creates temporary files in tmp. it never runs

Indeed Kubicle, that really helped. Gets me 1 step further in this journey into linux/ubuntu
and thank you Snowhog. I guess the man alone didn't give so much context as Kubicle provided

you two seem to understand cron quite well. Can you explain why Konsole launches as well as Ktorrent with message:
-------------------------------------------------------------------------
End of script execution. Type Enter or Ctrl+C to exit.
-------------------------------------------------------------------------

currently I use KAlarm to launch Ktorrent with the simple command "Ktorrent". Am I right in thinking that since KAlarm runs within the X session it is exempt from needing to specify displayname?

I was hoping to dump KAlarm and use cron since cron is already running in the background.
It appeared so simple at first but it seems I have a lot to learn about the commands I give it.
What language are these commands? unix? linux? ubuntu linux?

THANKS AGAIN

[kubicle]

Re: crontab -e only creates temporary files in tmp. it never runs

Am I right in thinking that since KAlarm runs within the X session it is exempt from needing to specify displayname?

yes

Can you explain why Konsole launches as well as Ktorrent with message:
-------------------------------------------------------------------------
End of script execution. Type Enter or Ctrl+C to exit.
-------------------------------------------------------------------------

Does this happen only when you start ktorrent via cron?
Does this happen with other programs if launched via cron?

You could try using this command to launch ktorrent (via cron):

/usr/bin/ktorrent --display :0 >> /dev/null 2>&1

(this will send all terminal output from ktorrent to "bit heaven" (/dev/null))

You can also direct the output to a file to see if there is anything of interest in the output:

/usr/bin/ktorrent --display :0 > ~/ktorrent_output.txt 2>&1

(this should write output to a file /home/username/ktorrent_output.txt)

Another thing you might have a go with is setting the $DISPLAY variable explicitly:

env DISPLAY=:0.0 /usr/bin/ktorrent > ~/ktorrent_output.txt 2>&1