[SOLVED] Automatic script execution !

[eaglelinux]

Hello !

How to make an " Automatic script execution " time based.
For example: Execute automaticly " backup.sh " everyday at 00:00 o'clock.

Thanks !

[glennzo]

I created a cron job for a specific task that I want to run once a day. As I recall, after a bit of research, all I did was add to /etc/crontab, like this:

SHELL=/bin/bash
PATH=/sbin:/bin:/usr/sbin:/usr/bin
MAILTO=root

# For details see man 4 crontabs

# Example of job definition:
# .---------------- minute (0 - 59)
# |  .------------- hour (0 - 23)
# |  |  .---------- day of month (1 - 31)
# |  |  |  .------- month (1 - 12) OR jan,feb,mar,apr ...
# |  |  |  |  .---- day of week (0 - 6) (Sunday=0 or 7) OR sun,mon,tue,wed,thu,fri,sat
# |  |  |  |  |
# *  *  *  *  * user-name  command to be executed
* 1 * * * root /usr/bin/rkhunter --propupd

The red line is, probably most obvious, the line I added. Given my understanding I assume that this will run every day at 1AM. This is my server so it's up 24/7. I believe that I needed to restart the crond service.

PHP Code:

systemctl restart crond.service 


My system logs tell me that this works as expected.

[stevea]

Also check out 'anacron' which fits some applications better.

[Adunaic]

You could also use crontab. This is user based.

to add/ edit a crontab entry do

crontab -e

to list current ones do

crontab -l

syntax for the jobs is the same as for cron in @bobs post.

Also - bewarned - crontab is very scary at first due to the fact that it uses 'vi'. To change this, type:

EDITOR=nano  #if you want nano
EDITOR='emacs -nw' #if you want emacs in terminal mode
EDITOR=emacs #if you want full emacs mode
EDITOR=vi # to change it back to vi

or any other editor you like.

[sea]

Oh crontab uses vi?
Never figured that one, as i simply did:

# Get current jobs:
  tmpfile=/tmp/cronjobs
  crontab -l > $tmpfile
# Edit the file
  gedit $tmpfile
# Save it back
  crontab $tmpfile

Replace gedit with any editor of your choice.

[jpollard]

I prefer having a backup of the crontab file anyway.

It works either way, but with a backup, I can restore the system and still not worry about loosing a crontab edit pass between backup and failure...

[Adunaic]

Originally Posted by sea

Oh crontab uses vi?
Never figured that one, as i simply did:

# Get current jobs:
  tmpfile=/tmp/cronjobs
  crontab -l > $tmpfile
# Edit the file
  gedit $tmpfile
# Save it back
  crontab $tmpfile

Replace gedit with any editor of your choice.

Oh sea. My oppinion of you just dropped a little - you wriet all those scripts and use gedit? Im not saying it has to be emacs, nano or vi. (cat and sed are acceptable editors!!!)

[sea]

Well to write scripts, i prefer easy marking and copy-paste.
And honestly, i cant friendly with emacs, tried a few times, but gedit is just much less than 1 minute setup and fits all my needs.
But hey, everyone has his own choice preferences.

[RupertPupkin]

Originally Posted by Adunaic

cat and sed are acceptable editors!!!

Bah, real programmers use ed; it's the standard text editor!

Like you I'm surprised that sea writes his scripts in gedit. I just assumed he used Microsoft Word with the Comic Sans font.

Actually that might be an interesting thread: what editor and font people use for programming. Emacs and DejaVu Sans Mono are of course the only correct answers, but it would be fun to see all the incorrect ones!

[Adunaic]

Originally Posted by RupertPupkin

Bah, real programmers use ed; it's the standard text editor!

Like you I'm surprised that sea writes his scripts in gedit. I just assumed he used Microsoft Word with the Comic Sans font.

Actually that might be an interesting thread: what editor and font people use for programming. Emacs and DejaVu Sans Mono are of course the only correct answers, but it would be fun to see all the incorrect ones!

No. Proper programmers use echo and get it right first time!!

[jpollard]

Of course, those using echo have to deal with various keyboard issues as well...

But then, they also know how to use head/tail commands to delete lines too

[Adunaic]

I had not thought about using head and tail to delete lines.

[jpollard]

One random puzzle challenge that came up at work (not a real problem) was how to do random record reads using the bourn shell.

The easy solution was "head -<number> file | tail -1" and that would be the record. The tail utility on Linux has the ability to do both at once, and simplifies the command considerably.

But editing a file still requires separate head/tail unless you use a rather complex awk script to insert the new data.

At one time, I had a cross reference tool for fortran that generated a "call by" table, and a "called by" table. The simplified parser only had to recognize subroutine calls (first pass identified function/subroutine names, then a second passes generated the lists. A third pass would collate the tables and generate the output, all using bourn shell scripts, awk, comm, and sort. Much faster than doing it by hand for required documents for a porting operation on an old HP3000 system.

[stevea]

Originally Posted by jpollard

One random puzzle challenge that came up at work (not a real problem) was how to do random record reads using the bourn shell.

The easy solution was "head -<number> file | tail -1" and that would be the record. The tail utility on Linux has the ability to do both at once, and simplifies the command considerably.

NO doesn't. 'tail' always prints the last N lines. N can be distance from the bottom or top, but it can't select a middle line.

But editing a file still requires separate head/tail unless you use a rather complex awk script to insert the new data.

sed -n 5,+0p /etc/fstab # print line 5
sed -n 5,7p /etc/fstab # print lines 5-7 inclusive

[jpollard]

Steve, you missed the word "insert". Also that sed is an editor.

And from the manpage on tail:

-n, --lines=K
output the last K lines, instead of the last 10; or use -n +K
to output lines starting with the Kth

Granted, I haven't tried it as that would seem a bit obscure.

BTW, "head -n" prints the first n lines of a file, "tail -1" prints the last line of the input. So "head -n | tail -1" prints only one line.

... seems the manpage for tail is flat out wrong. All it gives is a "invalid context" for the "or use" entry.