Is there a way to execute bash script when I click a program like NetBeans or DropBox on Ubuntu
and execute a bash script when exit it
My idea create bash script on cronjob #reboot check every second if the program exist in the current processes
#!/bin/bash
NameOfprogram="NetBeans"
while [[ true ]]; do
countOfprocess=$(ps -ef |grep $NameOfprogram | wc -l)
if [[ $countOfprocess -gt 1 ]]; then
#execute bash
fi
sleep 1
done
But I think this idea not the best ,Is there a better way to achieve it?
A better approach is to wrap the executable in a script. That means you put a script with the name of the program in your path (probably $HOME/bin) and Linux will use that instead of the real executable.
Now you can execute the real program using:
/usr/bin/NetBeans "$#"
So to execute the real executable, you just put the absolute path in front of the name. The odd "$#" too pass on any arguments someone might have given the script.
Put a loop around this:
while [[ true ]]; do
/usr/bin/NetBeans "$#"
done
But there is a problem: You can't exit this program anymore. As soon as you try, it restarts. So if you just want a restart when it crashes:
while [[ true ]]; do
/usr/bin/NetBeans "$#" && exit 0
done
As long as the program exits because of an error, it will be restarted. If you quit it, the script will stop.
Related
I have a folder of executable scripts, and some of them have Python shebangs, while others have Bash shebangs, etc. We have a cron job that runs this folder of scripts nightly, and the hope is that any error in any script will exit the job.
The scripts are run with something like: for FILE in $FILES; do ./$FILE; done
The scripts are provided by various people, and while the Python scripts always exit after an error, sometimes developers forget to add set -e in their Bash scripts.
I could have the for-loop use bash -e, but then I need to detect whether the current script is Bash/Python/etc.
I could set -e from the parent script, and then source scripts, but I still need to know which language each script is in, and I'd prefer them to run as subshells so script contributors don't have to worry about messing up the parent.
greping the shebangs is a short tweak, but knowing the flexibility of Bash, I'd be surprised if there weren't a way to "export" an option that affected all child scripts, in the same way you can export a variable. And, there have been many cases in general where I've forgotten "set -e", so it could be nice to know more options for fool-proofing things.
I see some options for inheriting -e for subshells involved in command substitution, but not in general.
Disclaimer: Never, ever do this! It's a huge disservice to everyone involved. You will introduce failures both in scripts with meticulous error handling, and in scripts without it.
Anyways, no one likes being told "don't do that" on StackOverflow, so my suggestion would be to identify scripts and invoke them with their shebang string plus -e:
for f in ./*
do
# Determine if the script is a shell script
if [[ $(file -i "$f") == *text/x-shellscript* ]]
then
# Read the first line
read -r shebang < "$f"
# The script shouldn't have been identified as a shell script without
# a shebang, but check anyways
if [[ $shebang != "#!"* ]]
then
echo "No idea what $f is" >&2
continue
fi
# Strip off the #! and run it with -e and the file
shebang=${shebang#??}
$shebang -e "$f"
else
# It's some other kind of executable, just run it directly
"$f"
fi
done
Here's a script with correct error handling that now stops working:
#!/bin/bash
my-service start
ret=$?
if [ $ret -eq 127 ]
then
# Use legacy invocation instead
start-my-service
ret=$?
fi
exit "$ret"
Here's a script without error handling that now stops working:
#!/bin/sh
err=$(grep "ERROR" file.log)
if [ -z "$err" ]
then
echo "Run was successful"
exit 0
else
echo "Run failed: $err"
exit 1
fi
I'm using Git Bash 2.9.0-64-bit in win7 64bit.
Here is my shell code
function sum1_x(){
a=$1
while [ $a -ge 1 ]; do
sum=$[$sum + $a]
a=$[$a - 1]
done
echo $sum
}
sum $1
In Git Bash,my type history is as follows:
wen#PC-WEN MINGW64 /d/git/ (dev)
$sh sum1_x.sh
exit
:q
quit
quit()
exit()
After I typed sh sum1_x.sh,I can no longer execute any shell command.I tried many commands as shows.I know there are bugs in my script,but how can I get back to execute shell script facing this kind of problems? Nothing can I do now.
You have several problems with your script:
you have function sum1_x but you are calling sum $1
You didn't check that input value exists, because of it you stuck in infinite loop
Here is the corrected script with check that input argument is exists:
function sum1_x(){
a=$1
while [ $a -ge 1 ]; do
sum=$[$sum + $a]
a=$[$a - 1]
done
echo $sum
}
if [ -z "$1" ]; then # check that input parameter is exists
echo "No input"
else
sum1_x $1
fi
How to stop program:
Ctrl + 'c'
Open new mingw and find pid of the progrman via ps -aux | grep "sum1_x.sh"
and then use kill pid to kill the program
As shows in the question,the shell script contains many bugs.The command sh sum1_x.sh was wrong too.It should be replaced by command sh sum1_x.sh 9 or things like it.After I fixed these bugs,it runs without problems and print the right sum.
But I still didn't know how to shop the shell script.Fortunately,By accident,I clicked Ctrl & c,and I can input shell commands again.
Having below sample script sample.sh
#!/bin/bash
if ps aux | grep -o "sample.sh" >/dev/null
then
echo "Already script running"
exit 0
fi
echo "start script"
while true
do
echo "script running"
sleep 5
done
In above script i want to check if this script previously running or not if running then not run it again.
problem is check condition always become true (because to check the condition require to run script) and it always show me "Already script running" message.
Any idea how to solve it?
You need a proper lock. I'd do using flock like this:
exec 201> /tmp/lock.$(basename $0).file
if ! flock -n 201 ; then
echo "another instance of $0 is running";
exit 1
fi
# cmds
exec 201>&-
rm -rf /tmp/lock.$(basename $0).file
This basically creates lock for script using a temporary file. The temporary file has particular significance other than it's used to tell whether your script has acquired a lock.
When there's an instance of this program running, the next run of the same program can't run as the lock will prevent it.
For me will be safer to use a lock file , create it when process start and delete after completion.
Let the script record its own PID in a file. Before doing so, it first checks if that file currently contains an active PID, in which case it exits.
pid=$(< ${PID_FILE:?} || exit
kill -0 $PID && exit
The next exercise is to prevent race conditions when writing the file.
Try this, it gives number of sample.sh run by the user
ps -aux | awk -v app='sample.sh' '$0 ~ app { print $1 }' |grep $USERNAME|wc -l
Wtite a tmp file to the /tmp directory.
have your script check to see if the file exists, if it does then don't run.
#!/bin/sh
# our tmpfile
tmpfile="/tmp/mytmpfile"
# check to see if it exists.
# if it does then exit script
if [[ -f ${tmpfile} ]]; then
echo script already running.
exit
fi
# it doesn't exist at this point so lets make one
touch ${tmpfile}
# do whatever now.
# end of script
rm ${tmpfile}
If i copy and paste all the commands into the terminal..
some do not even go through.
so the solution is perhaps to turn the file into an executable file
and then execute it.
but what if some commands fail.
the script keeps on executing the other commands.
obviously there is no solution to this right ?
The easiest way to do this is to use the -e option in your shell. For example:
#!/bin/sh -e
command1
command2
In this script, if command1 fails, then the script as a whole will fail at that point without running any further commands.
You can check the error code from commands you run
#!/bin/bash
function test {
"$#"
status=$?
if [ $status -ne 0 ]; then
echo "error with $1"
exit 255
fi
return $status
}
test ls
test ps -ef
test not_a_command
taken from here for more information Checking Bash exit status of several commands efficiently
#Terminal, you were almost there.
If you just stick && on the end of each command, then execution will stop with the first failure (ie. the first command that returns a non-zero exit code).
Example:
#!/bin/sh
true &&
echo 'got here' &&
echo 'got here too' &&
false &&
echo 'also got here'
produces the output
got here
got here too
(Actually, I thought it would also require line-continuation markers too: && \, but a quick test showed otherwise.)
Note: All of the above assumes that your shell is bash; I can't speak for other shells.
I am using the following to keep a single instance of a script running on my server. I have a cronjob to run this every minute.
How do I daemonize an arbitrary script in unix?
#!/bin/bash
if [[ $# < 1 ]]; then
echo "Name of pid file not given."
exit
fi
# Get the pid file's name.
PIDFILE=$1
shift
if [[ $# < 1 ]]; then
echo "No command given."
exit
fi
echo "Checking pid in file $PIDFILE."
#Check to see if process running.
PID=$(cat $PIDFILE 2>/dev/null)
if [[ $? = 0 ]]; then
ps -p $PID >/dev/null 2>&1
if [[ $? = 0 ]]; then
echo "Command $1 already running."
exit
fi
fi
# Write our pid to file.
echo $$ >$PIDFILE
# Get command.
COMMAND=$1
shift
# Run command
$COMMAND "$*"
Now I found out that my script had hung for some reason and therefore it was stuck. I'd like a way to check if the $PIDFILE is "old" and if so, kill the process. I know that's possible (check the timestamp on the file) but I don't know the syntax or if this is even a good idea. Also, when this script is running, the CPU should be pretty heavily used. If it hangs (rare but it happened at least once so far), the CPU usage drops to 0%. It would be nice if I could check that the process is really hung/not active, but I don't know if there's an easy way to do that (and I don't want to have many false positives where it gets killed but it's running fine).
To answer the question in your title, which seems quite different from your problem, use timeout.
Now, for your problem, I don't see where it could hang, unless you gave it a fifo queue for the pid file. Now, to run and respawn, you can just run this script once, on startup:
#!/bin/bash
while /bin/true; do
"$#"
wait
done
Which brings up another bug in the code you got from the other question: "$*" will pass all the arguments to the script as a single argument; without the quotes it'll split arguments with white space. "$#" will pass them individually and handling white space properly.
Call with /path/to/script command [argument]....