I have this terminal command show_space, when run, it will displays some stats such as how much disk space is used and left (in percentages, sizes etc) in my drive.
As I tried to put this command into a crontab as follows:
0 20 * 10 * show_space
I got the following error:
/bin/sh: show_space: command not found
Is it possible to integrate terminal based commands into crontab?
Related
I am facing an issue of crontab does not run the python script in Raspbian GNU/Linux 9.4 (stretch) installed on a Raspberry Pi3. I have done lots of research on this topic e.g. by following the troubleshooting guide in https://askubuntu.com/questions/23009/why-crontab-scripts-are-not-working/24527#24527 , but none of them solved my issue.
The python script that I want to run is located in
/home/pi/Documents/Fork_BookManager.py
I have made sure that anyone can execute, read and change content to the above file.
I can run this file through terminal by writing
usr/bin/python3 /home/pi/Documents/Fork_BookManager.py
I know the file is running, because the Fork_BookManager.py is using selenium to open a web browser, and I see this web browser being opened. There is no error observed when running the Fork_BookManager.py file from terminal.
In terminal executed
crontab -e
Using nano as editor, I first verified that crontab acutally worked by
* * * * * env > /home/pi/Documents/env.output
After a minute there is a env.output file in Documents folder with below parameters.
LANGUAGE=da_DK.UTF-8
HOME=/home/pi
LOGNAME=pi
PATH=/usr/bin:/bin
LANG=da_DK.UTF-8
SHELL=/bin/sh
LC_ALL=da_DK.UTF-8
PWD=/home/pi
I noticed that the path from crontab is different from the path when env is called from terminal as I will have the below path if I call env from terminal
PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/local/games:/usr/games
So I know that crontab -e was working since I otherwise would not have got the env.output file created in Documents folder. I proceed by calling crontab -e from terminal and copied the path from env into the crontab like below
PATH = /usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/local/games:/usr/games
* * * * * /usr/bin/python3 /home/pi/Documents/Fork_BookManager.py
Saved the script and waited. Nothing happend.
To summerize I have:
Made sure that the Fork_BookManager.py is executable
Verified that crontab is working
Updated path from env into the crontab script
which are three largest cause of experiencing difficulties in making crontab to work according to this guide
https://askubuntu.com/questions/23009/why-crontab-scripts-are-not-working/24527#24527
Still it is not working. What have I missed? Is there a better practice to achieve what I want, namely to execute the python script once a minute without doing it directly from the python script itself such as a while loop with a time.sleep(60)
ADDITIONAL INFORMATION
I even tried to expand the path in crontab script by
PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/local/games:/usr/games:/usr/bin:/home/pi/Documents
in an attempt to specify in which folder the python3 and Fork_BookManager.py is located. Still no luck.
I've sucessfully configured a script that scans my system using cron in a scheduled hour of a day. However, I would like to see the results that it might have generated with its execution. Ex: rkhunter -c leaves logs in /var/log/rkhunter.log that I manually would have to check after it performed the task.
How can I configure cron to show a terminal with its results for example?
I've seen a similar case to mine, but it didn't work:
minute hour * * * DISPLAY=:0 xterm -e /dir_to_my_script/script.sh
But it gave the following error that I've not been able to solve so far:
Warning: This program is an suid-root program or is being run by the root user.
The full text of the error or warning message cannot be safely formatted
in this environment. You may get a more descriptive message by running the
program as a non-root user or by removing the suid bit on the executable.
xterm: Xt error: Can't open display: %s
Is there a way to accomplish it using cron as root? Thanks
how to use crontab to run a Graphical program such as "gedit"
57 12 * * * gedit --display=localhost:0
Can not successfully open the program and display it.
--display=localhost:0 can be causing error ,
Following code will also do the trick
57 12 * * * export DISPLAY=:0 && /usr/bin/gedit
There is a reason why i added entire path of gedit ,
Utilities in /bin and /usr/bin can be opened using cron just by specifying its name so
/usr/bin/gedit or just gedit will work.
May a time command you use to start certain utility on terminal doesn't work using cron ,this is because cron passes a minimal set of environment variables to your jobs.May be required env PATH variable is not available with Cron hence it is not able to locate that utility.
you can find a detailed explanation in first reply here.
I made a shell script and registered to execute every 20 minutes.
Here is my crontab code.
*/20 * * * * sh /mypath/run_myprocess.sh &> /dev/pts/34
I editted code like this in order to see whether my process run correctly.
I get the result '/dev/pts/34' from tty command in terminal.
However, does anyone know how to use linux command results(in this case: /dev/pts/34)
in crontab? This is because I will use several terminal to run my tasks.
For example, in shell script, I can use linux command result in the form of $(command) such as
echo "$(date)"
directly.
Plus, if I type something on the terminal during process running with crontab, it actually gives result. For example,
Process is running........
ls
backup backup.sh Desktop Task_Folder shared_folder
[UserID] ~ #
So I guess cron jobs run correctly but in background.
Please help me to find out how can I bring cron jobs in foreground.
If you start a job on your console and background it you can then bring it to foreground. If the task is not yours or not started on your terminal then you can not.
I am using ubuntu 12.04.I am using a script(./home/sam/code/imageUpdate) to synchronising images from server to a particular folder in local system. And I have to run the script in the evening always. So I want to write a crontab which will automatically runs the script.
My commands :
$crontab -e;
And added the scheduled time to the crontab file.
# 50 17 * * * cd /home/sam
# 52 17 * * * ./code/imageUpdate > image1.txt
Then I saved the file and waited for the result.
But I didn't get any result. No image was been synchronised to image1.txt file.
Have I left any step ?
Please help me out...
Thanks in advance.
Make sure you don't have hashes (comments) at the start of your crontab commands.
Additionally:
Crontab commands should be run in isolation.
Each crontab command will be run in its own context, changing directory in one instruction probably won't lead to that directory being sound for the next executed (they may be run in their own environments, e.g.).
To overcome this, write a simple shell script which encompasses all of your commands for a single action.
# MyCommand.sh
cd /home/sam
./code/imageUpdate > image1.txt
# crontab command
50 17 * * * /home/sam/MyCommand.sh