A free Basic UNIX-training with muLinux

Automatic Execution of Programs

• Data protections
• Clearing up work in the directory system
• Statistics analyses of Internet accesses
• Status reports by email or SMS
• Fax dispatch
• Downloads

Daemons

For the time-controlled processing of programs is the daemons atd and crond responsible. One detects daemons to d> end.

In order to activate this Daemons under muLinux, we these must also setup start.

/# setup -f server
Do you want to change server/daemons setup? (y/n): y
Do you want to start XWindow server at any boot? (y/n): [Enter]
Do you want start atd daemon running? (y/n): y
Do you want start RING server running? (y/n): [Enter]
Do you want start SERIAL server running? (y/n): [Enter]
Do you want start DIALIN_SERVER running? (y/n): [Enter]
Do you want start FAX_SERVER running? (y/n): [Enter]
Do you want start TELNET_SERVER running? (y/n): [Enter]
Do you want start INETD_SERVER running? (y/n): [Enter]
Do you want start VCM_SERVER running? (y/n): [Enter]

/# setup -f crond
Do you want a running cron daemon? (y/n): y
Do you want to edit /etc/crontab now: n

We save our configuration.

/# setup -s tutorial01

Unique Execution of Processes with at at a Certain Time

/# at -h

The syntax of the muLinux version of the at deviates instruction from the normal version. Here is at to use as filters.

A tone is to ring out on 5. of the month at 04:00 am o'clock.

/#  echo ´wave -c 440´ | at 05 04:00

The computer is to be shutdown on 5. of the monthly at 05:00 pm.

/# echo ´halt´ | at 05 17:00

Each job receives a job number. The queue of the jobs leaves itself also atq display.

/# atq

In the directory /var/spool/atspool text files for the jobs are stored.

/# ls /var/spool/atspool

The name of the file corresponds to the pertinent job number. With less contents can be displayed.

/# cd /var/spool/atspool 
/# less job number

Jobs can be deleted also before the execution.

/#  atrm jobnumber

Note:
Also under Windows NT there is that in the DOS window at command in similar form. One could in such a way install on a NT computer the small muLinux. At the night then muLinux raising can leave automatically, in order to execute certain internal messages. By timing can then muLinux the computer again with NT start. So a whole operation system can function as a Trojan Horse.

Regular Execution of Processes with /etc/crontab

/# vi /etc/crontab

Here their contents:

# /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.
# This file also has a username field, 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
42  6  *   *   *  root  run-parts /etc/cron.daily
47  6  *   *   7  root  run-parts /etc/cron.weekly
52  6  1   *   *  root  run-parts /etc/cron.monthly

# test vari

#*/3 * * * *        root wave -c 220 4
#*/15 * * * *       root (wave -c 440 1; wave -c 880 3)
#*/2 * * * *        root echo "ciao" > /dev/console
#* */2 * * *        root mail -s "Da cron" root%Ciao, amico%

Comments begin also #. Each job is represented by a line. Whereby the following sequence to consider is (see comment line):

1. min = minute (number from 0 to 59)
2. h = hour (number from 0 to 23)
3. dom (day of the month) = day (number from 1 to 31)
4. month = month (number from 1 to 12)
5. dow (day of the week) = weekday (number of 0 = Sunday to 6=Sonnabend)
6. user = user
7. command = comand which can be required

An asterisk " * " is with all parameters for all possible in each case values.

In the first section the muLinux instruction becomes run parts called. This causes an executing of all programs in the indicated directories. In the above example thus all programs in the directory become at 6:42 o'clock each day /etc/cron.daily executed. Around 06:47 become at each 7. Day of the week (Sunday) all programs in the directory /etc/cron.weekly called. On the first day each monthly around 06:52 all programs become in /etc/cron.monthly started.

In the directory /etc/cron.daily is the example script Test . It has the following contents:

#!/bin/sh

#wave -c 440 1
#wave -c 880 3

It does not make nothing at all, since all lines are out-commentated. We can remove the comment in a line. So e.g. for wave - c 440 1. It sounded thus to each morning beep. That is perhaps no good idea.

We want to use the computer as bells. At each working-day it is to produce around 6:55 a tone.

#m h dom mon dow user        command
55 6 *   *   1-5 root   wave -c 220 4