Debian 8.6. No root.
I can use cron.
I need to check if application ( php ./somescript & ) running in background stopped, and restart it. How can I check it using bash?
Of course, there is ps aux | grep ....., but how do I automate it?
I suggest to take a look at keyword #reboot from man 5 crontab to start a job once at server startup.
One way to go about it would be:
Cron:
* * * * * env DISPLAY=:0 /folder/myscript >/dev/null 2>&1
The env DISPLAY=:0 might not be needed in your case, or it might be needed, depending on your script (note: you might need to adapt this to your case, run echo $DISPLAY to find out your variable on the case).
Script:
#!/bin/bash
testvar="$(ps aux | grep -s "somescript" | grep -sv "grep")"
if [ -z "$testvar" ]; then nohup /folder/somescript &; fi
exit 0
This all could and should be fine tuned to your needs, but I believe this example could serve you well.
Edit: I fixed a small oversight on the code (I added | grep -sv "grep" to get rid of the own grep process of looking for the file from the tesvar results).
Related
I would like to know if there is any simple script to automatically restart a screened background process.
The process gets killed but couldn't manage to create a successful one :(.
Thanks in advance! <3
I believe that the safest (but not the easiest) way to do this is to create a cron job to check if the process is running, and if it is not, restart it again. The reason why this method is "safer", is because if you use a loop like what ivanivan suggested and that script "crashes", the program will not be restarted again; on the other hand, by doing via cron, the check program will be called every minute.
For example, your cron could be:
* * * * * env DISPLAY=:0 /folder/testscript >/dev/null 2>&1
The env DISPLAY=:0 might not be needed in your case, or it might be needed, depending on your script (note: you might need to adapt this to your case, run echo $DISPLAY to find out your variable on the case).
For example, your testscript could be:
#!/bin/bash
testvar="$(ps aux | grep -s "mainscript" | grep -sv "grep -s mainscript")"
if [ -z "$testvar" ]; then nohup /folder/mainscript &; fi
#sleep and run second test
sleep 30
testvar="$(ps aux | grep -s "mainscript" | grep -sv "grep -s mainscript")"
if [ -z "$testvar" ]; then nohup /folder/mainscript &; fi
exit 0
On the example above, the testscript would check to see if the mainscript is running (and restart it if necessary) twice every minute.
What is the linux command to find if a process say aa.sh is running or not.
ps command does not seem to work and it does not show the shell script names.
Please advise.
Check this
ps aux | grep "aa.sh"
The simplest and efficient solution is :
pgrep -fl aa.sh
Adding to the answers above -
To use in a script, use the following :-
result=`ps aux | grep -i "myscript.sh" | grep -v "grep" | wc -l`
if [ $result -ge 1 ]
then
echo "script is running"
else
echo "script is not running"
fi
Check this
ps -ef | grep shellscripname.sh
You can also find your running process in
ps -ef
The solutions above are great for interactive use, where you can eyeball the result and weed out false positives that way.
False positives can occur if the executable itself happens to match, or any arguments that are not script names match - the likelihood is greater with scripts that have no filename extensions.
Here's a more robust solution for scripting, using a shell function:
getscript() {
pgrep -lf ".[ /]$1( |\$)"
}
Example use:
# List instance(s) of script "aa.sh" that are running.
getscript "aa.sh" # -> (e.g.): 96112 bash /Users/jdoe/aa.sh
# Use in a test:
if getscript "aa.sh" >/dev/null; then
echo RUNNING
fi
Matching is case-sensitive (on macOS, you could add -i to the pgrep call to make it case-insensitive; on Linux, that is not an option.)
The getscript function also works with full or partial paths that include the filename component; partial paths must not start with / and each component specified must be complete. The "fuller" the path specified, the lower the risk of false positives. Caveat: path matching will only work if the script was invoked with a path - this is generally true for scripts in the $PATH that are invoked directly.
Even this function cannot rule out all false positives, as paths can have embedded spaces, yet neither ps nor pgrep reflect the original quoting applied to the command line. All the function guarantees is that any match is not the first token (which is the interpreter), and that it occurs as a separate word, optionally preceded by a path.
Another approach to minimizing the risk of false positives could be to match the executable name (i.e., interpreter, such as bash) as well - assuming it is known; e.g.
# List instance(s) of a running *bash* script.
getbashscript() {
pgrep -lf "(^|/)bash( | .*/)$1( |\$)"
}
If you're willing to make further assumptions - such as script-interpreter paths never containing embedded spaces - the regexes could be made more restrictive and thus further reduce the risk of false positives.
pgrep -f aa.sh
To do something with the id, you pipe it. Here I kill all its child tasks.
pgrep aa.sh | xargs pgrep -P ${} | xargs kill
If you want to execute a command if the process is running do this
pgrep aa.sh && echo Running
I was quite inspired by the last answer by mklement0 - I have few scripts/small programs I run at every reboot via /etc/crontab. I built on his answer and built a login script, which shows if my programs are still running.
I execute this scripts.sh via .profile -file on every login, to get instant notification on each login.
cat scripts.sh
#!/bin/bash
getscript() {
pgrep -lf ".[ /]$1( |\$)"
}
script1=keepalive.sh
script2=logger_v3.py
# test if script 1 is running
if getscript "$script1" >/dev/null; then
echo "$script1" is RUNNING
else
echo "$script1" is NOT running
fi
# test if script 2 is running:
if getscript "$script2" >/dev/null; then
echo "$script2" is RUNNING
else
echo "$script2" is NOT running
fi
here a quick script to test if a shell script is running
#!/bin/sh
scripToTest="your_script_here.sh"
scriptExist=$(pgrep -f "$scripToTest")
[ -z "$scriptExist" ] && echo "$scripToTest : not running" || echo "$scripToTest : runnning"
Give an option to ps to display all the processes, an example is:
ps -A | grep "myshellscript.sh"
Check http://www.cyberciti.biz/faq/show-all-running-processes-in-linux/ for more info
And as Basile Starynkevitch mentioned in the comment pgrep is another solution.
I have a small script do count open files on Linux an save results into a flat file. I intend to run it on Cron every minute to gather results later. Script follows:
/bin/echo "Timestamp: ` date +"%m-%d-%y %T"` Files: `lsof | grep app | wc -l`"
And the crontab is this:
*/1 * * * * /usr/local/monitor/appmon.sh >> /usr/local/monitor/app_stat.txt
If I run from shell ./script.sh it works well and outputs as:
Timestamp: 01-31-13 09:33:59 Files: 57
But on the Cron output is:
Timestamp: 01-31-13 09:33:59 Files: 0
Not sure if any permissions are needed or similar. I have tried with sudo on lsof without luck as well.
Any hints?
from your working cmd-line, do
which lsof
which grep
which wc
which date
Take the full paths for each of these commands and add them into your shell script, producing something like
/bin/echo "Timestamp: `/bin/date +"%m-%d-%y %T"` Files: `/usr/sbin/lsof | /bin/grep app | /bin/wc -l`"
OR you can set a PATH var to include the missing values in your script, i.e.
PATH=/usr/sbin:${PATH}
Also unless you expect your script to be run from a true Bourne Shell environment, join the early 90's and use the form $( cmd ... ) for cmd-substitution, rather than backticks. The Ksh 93 book, published in 1995 remarks that backticks for command substitution are deprecated ;-)
IHTH
I have a script that I mean to be run from cron that ensures that a daemon that I wrote is working. The contents of the script file are similar to the following:
daemon_pid=`ps -A | grep -c fsdaemon`
echo "daemon_pid: " $daemon_pid
if [ $daemon_pid -eq 0 ]; then
echo "restarting fsdaemon"
/etc/init.d/fsdaemon start
fi
When I execute this script from the command prompt, the line that echoes the value of $daemon_pid is reporting a value of 2. This value is two regardless of whether my daemon is running or not. If, however, I execute the command with back quotes and then examine the $daemon_pid variable, the value of $daemon_pid is now one. I have also tried single stepping through the script using bashdb and, when I examine the variables using that tool, they are what they should be.
My question therefore is: why is there a difference in the behaviour between when the script is executed by the shell versus when the commands in the script are executed manually? I'm sure that there is something very fundamental that I am missing.
You're very likely encountering the grep as part of the 'answer' from ps.
To help fully understand what is happening, turn off the -c option, to see what data is being returned from just ps -A | grep fsdameon.
To solve the issue, some systems have a p(rocess)grep (pgrep). That will work, OR
ps -A | grep -v grep | grep -c fsdaemon
Is a common idiom you will see, but at the expense of another process.
The cleanest solution is,
ps -A | grep -c '[f]sdaemon'
The regular expression syntax should work with all greps, on all systems.
I hope this helps.
The problem is that grep itself shows up... Try running this command with anything after grep -c:
eple:~ erik$ ps -a | grep -c asdfladsf
1
eple:~ erik$ ps -a | grep -c gooblygoolbygookeydookey
1
eple:~ erik$
What does ps -a | grep fsdaemon return? Just look at the processes actually listed... :)
Since this is Linux, why not try the pgrep? This saves you a pipe, and you don't end up with grep reporting back the daemon script itself running.
Aany process with arguments including that name will add to the count - grep, and your script.
psing for a process isn't really reliable, you should use a lock file.
As several people have pointed out already, your process count is inflated because ps | grep detects (1) the script itself and (2) the subprocess created by the backquotes, which inherits the name of the main script. So an easy solution is to change the name of the script to something that doesn't include the name you're looking for. But you can do better.
The "best-practice" solution that I would suggest is to use the facilities provided by your operating system. It's not uncommon for an init script to create a PID file as part of the process of starting your daemon; in other words, instead of just running the daemon itself, you use a wrapper script that starts the daemon and then writes the process ID to a file somewhere. If start-stop-daemon exists on your system (and I think it's fairly common these days), you can use that like so:
start-stop-daemon --start --quiet --background \
--make-pidfile --pidfile /var/run/fsdaemon.pid -- /usr/bin/fsdaemon
(obviously replace the path /usr/bin/fsdaemon as appropriate) to start it, and then
start-stop-daemon --stop --quiet --pidfile /var/run/fsdaemon.pid
to stop it. start-stop-daemon has other options that might be useful to you, which you can investigate by reading the man page.
If you don't have access to start-stop-daemon, you can write a wrapper script to do basically the same thing, something like this to start:
echo "$$" > /var/run/fsdaemon.pid
exec /usr/bin/fsdaemon
and this to stop:
kill $(< /var/run/fsdaemon/pid)
rm /var/run/fsdaemon.pid
(this is pretty crude, of course, but it should normally work).
Anyway, once you have the setup to generate a PID file, whether by using start-stop-daemon or not, you can update your check script to this:
daemon_pid=`ps --no-headers --pid $(< /var/run/fsdaemon.pid) | wc -l`
if [ $daemon_pid -eq 0 ]; then
echo "restarting fsdaemon"
/etc/init.d/fsdaemon restart
fi
(one would think there would be a concise command to check whether a given PID is running, but I don't know it).
If you don't want to (or can't) create a PID file, I would at least suggest pgrep instead of ps | grep, since pgrep will search directly for a process by name and won't find anything that just happens to include the same string.
daemon_pid=`pgrep -x -c fsdaemon`
if [ $daemon_pid -eq 0 ]; then
echo "restarting fsdaemon"
/etc/init.d/fsdaemon restart
fi
The -x means "match exactly", and -c works as with grep.
By the way, it seems a bit misleading to name your variable daemon_pid when it is actually a count.
This
#!/bin/bash
if [ `ps -ef | grep "91.34.124.35" | grep -v grep | wc -l` -eq 0 ]; then sh home/asfd.sh; fi
or this?
ps -ef | grep "91\.34\.124\.35" | grep -v grep > /dev/null
if [ "$?" -ne "0" ]
then
sh home/asfd.sh
else
echo "Process is running fine"
fi
Hello, how can I write a shell script that looks in running processes and if there isn't a process name CONTAINING 91.34.124.35 then execute a file in a certain place and I want to make this run every 30 seconds in a continuous loop, I think there was a sleep command.
you can't use cron since on the implementation I know the smallest unit is one minute. You can use sleep but then your process will always be running (with cron it will started every time).
To use sleep just
while true ; do
if ! pgrep -f '91\.34\.124\.35' > /dev/null ; then
sh /home/asfd.sh
fi
sleep 30
done
If your pgrep has the option -q to suppress output (as on BSD) you can also use pgrep -q without redirecting the output to /dev/null
First of all, you should be able to reduce your script to simply
if ! pgrep "91\.34\.124\.35" > /dev/null; then ./your_script.sh; fi
To run this every 30 seconds via cron (because cron only runs every minute) you need 2 entries - one to run the command, another to delay for 30 seconds before running the same command again. For example:
* * * * * root if ! pgrep "91\.34\.124\.35" > /dev/null; then ./your_script.sh; fi
* * * * * root sleep 30; if ! pgrep "91\.34\.124\.35" > /dev/null; then ./your_script.sh; fi
To make this cleaner, you might be able to first store the command in a variable and use it for both entries. (I haven't tested this).
CHECK_COMMAND="if ! pgrep '91\.34\.124\.35' > /dev/null; then ./your_script.sh; fi"
* * * * * root eval "$CHECK_COMMAND"
* * * * * root sleep 30; eval "$CHECK_COMMAND"
p.s. The above assumes you're adding that to /etc/crontab. To use it in a user's crontab (crontab -e) simply leave out the username (root) before the command.
I would suggest using watch:
watch -n 30 launch_my_script_if_process_is_dead.sh
Either way is fine, you can save it in a .sh file and add it to the crontab to run every 30 seconds. Let me know if you want to know how to use crontab.
Try this:
if ps -ef | grep "91\.34\.124\.35" | grep -v grep > /dev/null
then
sh home/asfd.sh
else
echo "Process is running fine"
fi
No need to use test. if itself will examine the exit code.
You can save your script in file name, myscript.sh
then you can run your script through cron,
*/30 * * * * /full/path/for/myscript.sh
or you can use while
# cat script1.sh
#!/bin/bash
while true; do /bin/sh /full/path/for/myscript.sh ; sleep 30; done &
# ./script1.sh
Thanks.
I have found deamonizing critical scripts very effective.
http://cr.yp.to/daemontools.html
You can use monit for this task. See docu. It is available on most linux distributions and has a straightforward config. Find some examples in this post
For your app it will look something like
check process myprocessname
matching "91\.34\.124\.35"
start program = "/home/asfd.sh"
stop program = "/home/dfsa.sh"
If monit is not available on your platform you can use supervisord.
I also found this question very similar Repeat command automatically in Linux. It suggests to use watch.
Use cron for the "loop every 30 seconds" part.