This question has boring me a whole day...
I want to modify root's environment variables $bai automatically, and I write a shell script and add it to root's crontab. but $bai is not changed.
here is my script /root/111.sh:
#!/bin/bash
time=`date`
export bai=$time
here is the crontab:
*/1 * * * * . /root/111.sh
Then echo $bai is null
but when I source /root/111.sh and echo $bai, it can get the time: Wed Dec 24 17:02:48 CST 2014
So how can I get the environment variables by use it in my cron job?
You cannot change variables in a different process like that. Probably the nearest you can do is to use a file, something like this.
In crontab:
* * * * * /bin/date > /tmp/value.txt
In some other script:
#!/bin/bash
while :; do
v=$(cat /tmp/value.txt)
echo $v
sleep 1
done
What I suppose you do is to modify exported variables. But there's no way to a child process to modify environment of a parent process. The only way to set variables is from parent.
The problem is because you are in 2 different bash. The crontab issues the command and export the variable $bai to the current session that just opened and then exits, and with it the initialized $bai, that's why when you do it locally by issuing source /root/111.sh you see that the $bai is created, because you are creating the variable in your bash session.
If you want to have the $bai variable every time you open a bash session, you need to add it in .bashrc file that is in your home directory by adding
echo "export bai=\`date\`" >> ~/.bashrc
Every time you start a bash if you issue echo $bai, you'll get the date... BUT if you want the $bai variable being updated every x time, then this approach is not correct as it will keep the date when you logged in, and crontab is not going to help you because of my first explanation.
Related
I'm trying to get cron to call in the correct PATHs. When I run a Python script from shell the script runs fine as it uses the PATHs set in bashrc but when I use cron all the PATHs are not used from bashrc. Is there a file I can enter the PATHs into for cron like bashrc or a way to call the PATHs from bashrc?
Sorry I don't think I worded this correctly, I can get the correct script to run (meaning the PATH to the script in crontab is not the problem here), it's just when that script is running I run a build and this uses the PATHs set in .bashrc. When I run the script when I'm logged in, the .bashrc PATHs are pulled in. Since cron doesn't run in a shell per say it does not pull in .bashrc. Is there a way of pulling this in without having to write a bash script wrapper?
I used /etc/crontab. I used vi and entered in the PATHs I needed into this file and ran it as root. The normal crontab overwrites PATHs that you have set up. A good tutorial on how to do this.
The systemwide cron file looks like this:
This has the username field, as used by /etc/crontab.
# /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 --report /etc/cron.daily
47 6 * * 7 root run-parts --report /etc/cron.weekly
52 6 1 * * root run-parts --report /etc/cron.monthly
01 01 * * 1-5 root python /path/to/file.py
Most likely, cron is running in a very sparse environment. Check the environment variables cron is using by appending a dummy job which dumps env to a file like this:
* * * * * env > env_dump.txt
Compare that with the output of env in a normal shell session.
You can prepend your own environment variables to the local crontab by defining them at the top of your crontab.
Here's a quick fix to prepend $PATH to the current crontab:
# echo PATH=$PATH > tmp.cron
# echo >> tmp.cron
# crontab -l >> tmp.cron
# crontab tmp.cron
The resulting crontab will look similar to chrissygormley's answer, with PATH defined before the crontab rules.
You should put full paths in your crontab. That's the safest option.
If you don't want to do that you can put a wrapper script around your programs, and set the PATH in there.
e.g.
01 01 * * * command
becomes:
01 01 * * * /full/path/to/command
Also anything called from cron should be be very careful about the programs it runs, and probably set its own choice for the PATH variable.
EDIT:
If you don't know where the command is that you want execute which <command> from your shell and it'll tell you the path.
EDIT2:
So once your program is running, the first thing it should do is set PATH and any other required variable (e.g. LD_LIBRARY_PATH) to the values that are required for the script to run.
Basically instead of thinking how to modify the cron environment to make it more suitable for your program/script - make your script handle the environment it's given, by setting an appropriate one when it starts.
Adding a PATH definition into the user crontab with correct values will help...
I've filled mine with this line on top (after comments, and before cron jobs):
PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
And it's enough to get all my scripts working... Include any custom path there if you need to.
Setting PATH right before the command line in my crontab worked for me:
* * * * * PATH=$PATH:/usr/local/bin:/path/to/some/thing
Make your variables work for you, this will allow access t
Define your PATH in /etc/profile.d/*.sh
System-wide environment variables
Files with the .sh extension in the /etc/profile.d directory get executed whenever a bash login shell is entered (e.g. when logging in from the console or over ssh), as well as by the DisplayManager when the desktop session loads.
You can for instance create the file /etc/profile.d/myenvvars.sh and set variables like this:
export JAVA_HOME=/usr/lib/jvm/jdk1.7.0
export PATH=$PATH:$JAVA_HOME/bin
Execute crontab with login option!
CRONTAB run script or command with Environment Variables
0 9 * * * cd /var/www/vhosts/foo/crons/; bash -l -c 'php -f ./download.php'
0 9 * * * cd /var/www/vhosts/foo/crons/; bash -l -c download.sh
Problem
Your script works when you run it from the console but fails in cron.
Cause
Your crontab doesn't have the right path variables (and possibly shell)
Solution
Add your current shell and path the crontab
Script to do it for you
#!/bin/bash
#
# Date: August 22, 2013
# Author: Steve Stonebraker
# File: add_current_shell_and_path_to_crontab.sh
# Description: Add current user's shell and path to crontab
# Source: http://brakertech.com/add-current-path-to-crontab
# Github: hhttps://github.com/ssstonebraker/braker-scripts/blob/master/working-scripts/add_current_shell_and_path_to_crontab.sh
# function that is called when the script exits (cleans up our tmp.cron file)
function finish { [ -e "tmp.cron" ] && rm tmp.cron; }
#whenver the script exits call the function "finish"
trap finish EXIT
########################################
# pretty printing functions
function print_status { echo -e "\x1B[01;34m[*]\x1B[0m $1"; }
function print_good { echo -e "\x1B[01;32m[*]\x1B[0m $1"; }
function print_error { echo -e "\x1B[01;31m[*]\x1B[0m $1"; }
function print_notification { echo -e "\x1B[01;33m[*]\x1B[0m $1"; }
function printline {
hr=-------------------------------------------------------------------------------------------------------------------------------
printf '%s\n' "${hr:0:${COLUMNS:-$(tput cols)}}"
}
####################################
# print message and exit program
function die { print_error "$1"; exit 1; }
####################################
# user must have at least one job in their crontab
function require_gt1_user_crontab_job {
crontab -l &> /dev/null
[ $? -ne 0 ] && die "Script requires you have at least one user crontab job!"
}
####################################
# Add current shell and path to user's crontab
function add_shell_path_to_crontab {
#print info about what's being added
print_notification "Current SHELL: ${SHELL}"
print_notification "Current PATH: ${PATH}"
#Add current shell and path to crontab
print_status "Adding current SHELL and PATH to crontab \nold crontab:"
printline; crontab -l; printline
#keep old comments but start new crontab file
crontab -l | grep "^#" > tmp.cron
#Add our current shell and path to the new crontab file
echo -e "SHELL=${SHELL}\nPATH=${PATH}\n" >> tmp.cron
#Add old crontab entries but ignore comments or any shell or path statements
crontab -l | grep -v "^#" | grep -v "SHELL" | grep -v "PATH" >> tmp.cron
#load up the new crontab we just created
crontab tmp.cron
#Display new crontab
print_good "New crontab:"
printline; crontab -l; printline
}
require_gt1_user_crontab_job
add_shell_path_to_crontab
Source
https://github.com/ssstonebraker/braker-scripts/blob/master/working-scripts/add_current_shell_and_path_to_crontab.sh
Sample Output
The simplest workaround I've found looks like this:
* * * * * root su -l -c command
This example invokes su as root user and starts the shell with the user's full environment, including $PATH, set as if they were logged in. It works the same on different distros, is more reliable than sourcing .bashrc (which hasn't worked for me) and avoids hardcoding specific paths which can be a problem if you're providing an example or setup tool and don't know what distro or file layout on the user's system.
You can also specify the username after su if you want a different user than root, but you should probably leave the root parameter before su command since this ensures su has sufficient privileges to switch to any user you specify.
The default environment for cron jobs is very sparse and may be very different from the environment you develop your python scripts in. For a script that might be run in cron, any environment that you depend on should be set explicitly. In the cron file itself, include full paths to python executables and to your python scripts.
On my AIX cron picks up it's environmental variables from /etc/environment ignoring what is set in the .profile.
Edit: I also checked out a couple of Linux boxes of various ages and these appear to have this file as well, so this is likely not AIX specific.
I checked this using joemaller's cron suggestion and checking the output before and after editing the PATH variable in /etc/environment.
If you don't want to have to make the same edits in various places, then roughly do this:
* * * * * . /home/username/.bashrc && yourcommand all of your args
The . space and then the path to .bashrc and the && command are the magic there to get your environment changes into the running bash shell. Too, if you really want the shell to be bash, it is a good idea to have a line in your crontab:
SHELL=/bin/bash
Hope it helps someone!
#Trevino: your answer helped me solve my problem. However, for a beginner, trying to give a step by step approach.
Get your current installation of java via $ echo $JAVA_HOME
$ crontab -e
* * * * * echo $PATH - this lets you understand whats the PATH value being used by crontab at present. Run crontab and grab $PATH value used by crontab.
Now edit crontab again to set your desired java bin path: a) crontab -e; b) PATH=<value of $JAVA_HOME>/bin:/usr/bin:/bin (its a sample path); c) now your scheduled job/script like */10 * * * * sh runMyJob.sh &; d) remove echo $PATH from crontab as its not needed now.
Set the required PATH in your cron
crontab -e
Edit: Press i
PATH=/usr/local/bin:/usr/local/:or_whatever
10 * * * * your_command
Save and exit :wq
I know this has been answered already, but I thought that his would be useful to some. I had a similar issue that I recently solved (found here) and here are the highlights of the steps I took to answer this question:
make sure that you have the variables you need in PYTHONPATH (found here and here and for more info here) inside the .profile or .bash_profile for any shell you want to test your script in to make sure it works.
edit your crontab to include the directories needed to run your script in a cron job (found here and here)
a) be sure to include the root directory in the PATH variable (.) as explained here (basically if you are running an executable with your command it needs to be able to find root or the directory where the executable is stored) and probably these (/sbin:/bin:/usr/sbin:/usr/bin)
in your crontab file, create a cronjob that will change directory to the directory where you have successfully ran the script before (i.e. Users/user/Documents/foo)
a) This will look like the following:
* * * * cd /Users/user/Documents/foo; bar -l doSomething -v
Should you use webmin then these are the steps how to set the PATH value:
System
-> Scheduled Cron Jobs
-> Create a new environment variable
-> For user: <Select the user name>
-> Variable name: PATH
-> Value: /usr/bin:/bin:<your personal path>
-> Add environment variable: Before all Cron jobs for user
I'm trying to get cron to call in the correct PATHs. When I run a Python script from shell the script runs fine as it uses the PATHs set in bashrc but when I use cron all the PATHs are not used from bashrc. Is there a file I can enter the PATHs into for cron like bashrc or a way to call the PATHs from bashrc?
Sorry I don't think I worded this correctly, I can get the correct script to run (meaning the PATH to the script in crontab is not the problem here), it's just when that script is running I run a build and this uses the PATHs set in .bashrc. When I run the script when I'm logged in, the .bashrc PATHs are pulled in. Since cron doesn't run in a shell per say it does not pull in .bashrc. Is there a way of pulling this in without having to write a bash script wrapper?
I used /etc/crontab. I used vi and entered in the PATHs I needed into this file and ran it as root. The normal crontab overwrites PATHs that you have set up. A good tutorial on how to do this.
The systemwide cron file looks like this:
This has the username field, as used by /etc/crontab.
# /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 --report /etc/cron.daily
47 6 * * 7 root run-parts --report /etc/cron.weekly
52 6 1 * * root run-parts --report /etc/cron.monthly
01 01 * * 1-5 root python /path/to/file.py
Most likely, cron is running in a very sparse environment. Check the environment variables cron is using by appending a dummy job which dumps env to a file like this:
* * * * * env > env_dump.txt
Compare that with the output of env in a normal shell session.
You can prepend your own environment variables to the local crontab by defining them at the top of your crontab.
Here's a quick fix to prepend $PATH to the current crontab:
# echo PATH=$PATH > tmp.cron
# echo >> tmp.cron
# crontab -l >> tmp.cron
# crontab tmp.cron
The resulting crontab will look similar to chrissygormley's answer, with PATH defined before the crontab rules.
You should put full paths in your crontab. That's the safest option.
If you don't want to do that you can put a wrapper script around your programs, and set the PATH in there.
e.g.
01 01 * * * command
becomes:
01 01 * * * /full/path/to/command
Also anything called from cron should be be very careful about the programs it runs, and probably set its own choice for the PATH variable.
EDIT:
If you don't know where the command is that you want execute which <command> from your shell and it'll tell you the path.
EDIT2:
So once your program is running, the first thing it should do is set PATH and any other required variable (e.g. LD_LIBRARY_PATH) to the values that are required for the script to run.
Basically instead of thinking how to modify the cron environment to make it more suitable for your program/script - make your script handle the environment it's given, by setting an appropriate one when it starts.
Adding a PATH definition into the user crontab with correct values will help...
I've filled mine with this line on top (after comments, and before cron jobs):
PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
And it's enough to get all my scripts working... Include any custom path there if you need to.
Setting PATH right before the command line in my crontab worked for me:
* * * * * PATH=$PATH:/usr/local/bin:/path/to/some/thing
Make your variables work for you, this will allow access t
Define your PATH in /etc/profile.d/*.sh
System-wide environment variables
Files with the .sh extension in the /etc/profile.d directory get executed whenever a bash login shell is entered (e.g. when logging in from the console or over ssh), as well as by the DisplayManager when the desktop session loads.
You can for instance create the file /etc/profile.d/myenvvars.sh and set variables like this:
export JAVA_HOME=/usr/lib/jvm/jdk1.7.0
export PATH=$PATH:$JAVA_HOME/bin
Execute crontab with login option!
CRONTAB run script or command with Environment Variables
0 9 * * * cd /var/www/vhosts/foo/crons/; bash -l -c 'php -f ./download.php'
0 9 * * * cd /var/www/vhosts/foo/crons/; bash -l -c download.sh
Problem
Your script works when you run it from the console but fails in cron.
Cause
Your crontab doesn't have the right path variables (and possibly shell)
Solution
Add your current shell and path the crontab
Script to do it for you
#!/bin/bash
#
# Date: August 22, 2013
# Author: Steve Stonebraker
# File: add_current_shell_and_path_to_crontab.sh
# Description: Add current user's shell and path to crontab
# Source: http://brakertech.com/add-current-path-to-crontab
# Github: hhttps://github.com/ssstonebraker/braker-scripts/blob/master/working-scripts/add_current_shell_and_path_to_crontab.sh
# function that is called when the script exits (cleans up our tmp.cron file)
function finish { [ -e "tmp.cron" ] && rm tmp.cron; }
#whenver the script exits call the function "finish"
trap finish EXIT
########################################
# pretty printing functions
function print_status { echo -e "\x1B[01;34m[*]\x1B[0m $1"; }
function print_good { echo -e "\x1B[01;32m[*]\x1B[0m $1"; }
function print_error { echo -e "\x1B[01;31m[*]\x1B[0m $1"; }
function print_notification { echo -e "\x1B[01;33m[*]\x1B[0m $1"; }
function printline {
hr=-------------------------------------------------------------------------------------------------------------------------------
printf '%s\n' "${hr:0:${COLUMNS:-$(tput cols)}}"
}
####################################
# print message and exit program
function die { print_error "$1"; exit 1; }
####################################
# user must have at least one job in their crontab
function require_gt1_user_crontab_job {
crontab -l &> /dev/null
[ $? -ne 0 ] && die "Script requires you have at least one user crontab job!"
}
####################################
# Add current shell and path to user's crontab
function add_shell_path_to_crontab {
#print info about what's being added
print_notification "Current SHELL: ${SHELL}"
print_notification "Current PATH: ${PATH}"
#Add current shell and path to crontab
print_status "Adding current SHELL and PATH to crontab \nold crontab:"
printline; crontab -l; printline
#keep old comments but start new crontab file
crontab -l | grep "^#" > tmp.cron
#Add our current shell and path to the new crontab file
echo -e "SHELL=${SHELL}\nPATH=${PATH}\n" >> tmp.cron
#Add old crontab entries but ignore comments or any shell or path statements
crontab -l | grep -v "^#" | grep -v "SHELL" | grep -v "PATH" >> tmp.cron
#load up the new crontab we just created
crontab tmp.cron
#Display new crontab
print_good "New crontab:"
printline; crontab -l; printline
}
require_gt1_user_crontab_job
add_shell_path_to_crontab
Source
https://github.com/ssstonebraker/braker-scripts/blob/master/working-scripts/add_current_shell_and_path_to_crontab.sh
Sample Output
The simplest workaround I've found looks like this:
* * * * * root su -l -c command
This example invokes su as root user and starts the shell with the user's full environment, including $PATH, set as if they were logged in. It works the same on different distros, is more reliable than sourcing .bashrc (which hasn't worked for me) and avoids hardcoding specific paths which can be a problem if you're providing an example or setup tool and don't know what distro or file layout on the user's system.
You can also specify the username after su if you want a different user than root, but you should probably leave the root parameter before su command since this ensures su has sufficient privileges to switch to any user you specify.
The default environment for cron jobs is very sparse and may be very different from the environment you develop your python scripts in. For a script that might be run in cron, any environment that you depend on should be set explicitly. In the cron file itself, include full paths to python executables and to your python scripts.
On my AIX cron picks up it's environmental variables from /etc/environment ignoring what is set in the .profile.
Edit: I also checked out a couple of Linux boxes of various ages and these appear to have this file as well, so this is likely not AIX specific.
I checked this using joemaller's cron suggestion and checking the output before and after editing the PATH variable in /etc/environment.
If you don't want to have to make the same edits in various places, then roughly do this:
* * * * * . /home/username/.bashrc && yourcommand all of your args
The . space and then the path to .bashrc and the && command are the magic there to get your environment changes into the running bash shell. Too, if you really want the shell to be bash, it is a good idea to have a line in your crontab:
SHELL=/bin/bash
Hope it helps someone!
#Trevino: your answer helped me solve my problem. However, for a beginner, trying to give a step by step approach.
Get your current installation of java via $ echo $JAVA_HOME
$ crontab -e
* * * * * echo $PATH - this lets you understand whats the PATH value being used by crontab at present. Run crontab and grab $PATH value used by crontab.
Now edit crontab again to set your desired java bin path: a) crontab -e; b) PATH=<value of $JAVA_HOME>/bin:/usr/bin:/bin (its a sample path); c) now your scheduled job/script like */10 * * * * sh runMyJob.sh &; d) remove echo $PATH from crontab as its not needed now.
Set the required PATH in your cron
crontab -e
Edit: Press i
PATH=/usr/local/bin:/usr/local/:or_whatever
10 * * * * your_command
Save and exit :wq
I know this has been answered already, but I thought that his would be useful to some. I had a similar issue that I recently solved (found here) and here are the highlights of the steps I took to answer this question:
make sure that you have the variables you need in PYTHONPATH (found here and here and for more info here) inside the .profile or .bash_profile for any shell you want to test your script in to make sure it works.
edit your crontab to include the directories needed to run your script in a cron job (found here and here)
a) be sure to include the root directory in the PATH variable (.) as explained here (basically if you are running an executable with your command it needs to be able to find root or the directory where the executable is stored) and probably these (/sbin:/bin:/usr/sbin:/usr/bin)
in your crontab file, create a cronjob that will change directory to the directory where you have successfully ran the script before (i.e. Users/user/Documents/foo)
a) This will look like the following:
* * * * cd /Users/user/Documents/foo; bar -l doSomething -v
Should you use webmin then these are the steps how to set the PATH value:
System
-> Scheduled Cron Jobs
-> Create a new environment variable
-> For user: <Select the user name>
-> Variable name: PATH
-> Value: /usr/bin:/bin:<your personal path>
-> Add environment variable: Before all Cron jobs for user
I'm trying to qsub a script within crontab. Within a crontab txt file, I tried:
0 1 * * * qsub /script.sh
The error I get is "/bin/sh: qsub: command not found."
I've tried a bunch of similar iterations and looked around online without success. I'd appreciate any help.
Programs executed under cron run with a limited set of environment variables. In particular, since it doesn't read your shell startup files (.bashrc, .profile, .cshrc, whatever), it won't have your $PATH settings; $PATH is likely to be something simple like /usr/bin:/bin.
You can set the PATH for a single command like this:
0 1 * * * PATH=/directory/containing/qsub:/usr/bin:/bin qsub /script.sh
You can also set environment variables globally; such settings will apply to all commands executed from your crontab:
PATH=/directory/containing/qsub:/usr/bin:/bin
0 1 * * * qsub /script.sh
man 5 crontab, or see here, for more information on writing crontabs.
If you want to see just what the environment for a cron job looks like, you can temporarily add this line to your crontab:
* * * * * printenv > cron-env
Wait until the top of the next minute, then cat ~/cron-env -- and then remove that line from your crontab so it doesn't keep executing.
(Is your script really in the root directory? Why isn't it under your home directory?)
The method works for me is that I first source the sge.sh under /etc/profile.d/sge.sh
Then the crontab will get the correct environment variable and able to run the qsub under crontab.
I have a shell script that exports values of variables when executed. The same values will be used in another script.
How to run this script(test.sh) in cron.
#!/bin/sh
export I="10"
echo $I
I will be using root access for cron.
I tried this command :
*/5 * * * * /home/ubuntu/backup/.test.sh
I checked with environment variables, nothing is updated.
Why .test.sh if the script is just test.sh?
Anyway... exported variables life ends when the process that set it exit.
In your case the I var disappears when test.sh script exit
If you want to your scripts access to the I value, you have to source the test.sh file (e.g. . /home/ubuntu/backup/test.sh) and not execute it.
Otherwise you can set it into .bashrc file
I have a script that requires the env variable USER to be set. As the script is used by several users, I can't just do export USER=xxx at the beginning of the script. I could define in the crontab, but I was just wondering whether there is a good way of pulling it in.
I tried sourcing .bashrc and .profile, but neither define USER, plus on Ubuntu .bashrc simply returns on non-interactive shells.
You could work around it by writing at the top of the script (Bashism):
USER=$(whoami)
or old-style:
USER=`whoami`
... assuming you have whoami in the PATH, which can also be set in the crontab just like several (most?) other variables. I.e. you can also set the variable in crontab itself (at least in Vixies cron) - see here for example.
Use the env command. Your crontab entry could look like:
* * * * * env USER=foouser /path/to/script.sh
You can specify environment variable before the command. This way, it won't affect anything else in the crontab.
user.sh:
#!/bin/sh
echo $USER
cli:
USER=foo ./user.sh ## outputs "foo"