I have a working shell script which calls another shell script to perform some action on some processes running on the server. This inner shell script sometimes prompt to enter the userid and password. If this happens I want to come out this inner script and want to perform kill -9 for the process. Can anyone please suggest on how to achieve this?
One more point, whatever my shell scripts does, I am recording this in a log file,so I assume when script prompts to enter userid and password, this info also get recorded in the log.So is their should be a way to check this in the log file.
I am working on Linux OS. Please check and advise.
You can kill your child script
after some timeout:
( cmdpid=$BASHPID; (sleep 10; kill -9 $cmdpid) & exec my-child-script )
In this case you will kill my-child-script after given period of time (10 sec).
You can't (easily) detect if you script is waiting for input (on standard input), the only working method is to use strace/ptrace, but it's too complex
and I don't think it's really worth it. The timeout-based approach seems to be by far more natural.
You can find here
some additional examples of this approach in this question:
Bash script that kills a child process after a given timeout
Regarding log files:
You can extract data from your log files using grep/sed. To make the answer more concrete, we need some extra data.
Related
Im an end user that has access to Putty in order to run selective scripts on our server as they would run during our overnight batch process.
Some of these I run in sequence using
run_process.ksh kj_job1 & wait; run_process.ksh kj_job2
However kj_job1 can fail and kj_job2 would still run. Id like a way for kj_job2 to only proceed if kj_job1 was completed succesfully but i cant find a guide online to walk me through what i need to do.
My knowledge in this area is limited, i simply navigate to the directory where we have the file run_process.ksh and then add the job name i want to run. I recently found out about the & wait command in order to run strings and the () s i can run things in parallel.
Any help is apprecaited.
I'm trying to have data (generated by an application only after its launch) persisted across multiple invocations of an application, but only when they're started from the same shell session.
One possible way to do that would be to pass the data back from the application to the calling shell, but since environment variable changes are only passed from parent to child, I don't know how to implement that.
Practical example:
There is job command that create subdirectory with current datetime and does work inside. Sometimes job needs to be killed and restarted, so it need directory where if finished, like job --resume 21Fri_1849/data. I would like to save 21Jan_1849/data so I don't have to check and type it each time I need to resume job. If I created something like .last_job, and wanted to restart job in another session, it could resume wrong (last) job, so files are not solution (AFAIK).
How can this be done?
Since you're only trying to target Linux, there are a fair number of tricks available here. Consider this one:
#!/usr/bin/env bash
current_boot_id=$(</proc/sys/kernel/random/boot_id)
# honor myprog_shell_pid if set and valid, fall back to PPID otherwise
if [[ $myprog_shell_pid ]] && [[ -e /proc/$myprog_shell_pid/stat ]]; then
parent_pid=$myprog_shell_pid
else
parent_pid=$PPID
fi
parent_start_time=$(awk '{print $22}' "/proc/$parent_pid/stat")
mkdir -p "$HOME/.cache/myscript-sessions"
data=$HOME/.cache/myscript-sessions/${current_boot_id}:${parent_pid}:${parent_start_time}
Now, we have a data file name that changes:
When we're rebooted (because current_boot_id is updated)
If we're run from a different shell (because our PPID changes).
If we're run from a different shell with the same PID (because the start time for the parent PID will be different).
...and you can easily delete files with the wrong boot id (because the system rebooted), or with names that refer to PID/start-time combinations that don't exist.
One caveat is that by default, this is sensitive to being called by subshells (output=$(./yourprog) will have a different PPID than ./yourprog will), but if the parent shell runs export myprog_shell_pid=$$, that issue goes away.
You're crossing over to where you need a simple job management engine instead of just shell. Using 'make' and writing Makefiles is the probably the simplest way to set this up. You can write a rule that tells how to turn a stage 1 file into a stage 2 file based on file extension, and then make will know how far things got and how to resume next time you run it.
I'm working on a server bot in python3 (using asyncio), and I would like to incorporate an update function for collaborators to instantly test their contributions. It is hosted on a VPS that I access via ssh. I run the process in tmux and it is often difficult for other contributors to relaunch the script once they have made a commit, etc. I'm very new to python, and I just use what I can find. So far I have used subprocess.Popen to run git pull, but I have no way for it to automatically restart the script.
Is there any way to terminate a running asyncio loop (ideally without errors) and restart it again?
You can not start a event loop stopped by event_loop.stop()
And in order to incorporate the changes you have to restart the script anyways (some methods might not exist on the objects you have, etc.)
I would recommend something like:
asyncio.ensure_future(git_tracker)
async def git_tracker():
# check for changes in version control, maybe wait for a sync point and then:
sys.exit(0)
This raises SystemExit, but despite that exits the program cleanly.
And around the python $file.py a while true; do git pull && python $file.py ; done
This is (as far as I know) the simplest approach to solve your problem.
For your use case, to stay on the safe side, you would probably need to kill the process and relaunch it.
See also: Restart process on file change in Linux
As a necromancer, I thought I give an up-to-date solution which we use in our UNIX system.
Using the os.execl function you can tell python to replace the current process with a new one:
These functions all execute a new program, replacing the current process; they do not return. On Unix, the new executable is loaded into the current process, and will have the same process id as the caller. Errors will be reported as OSError exceptions.
In our case, we have a bash script which executes the killall python3.7, sending the SIGTERM signal to our python apps which in turn listen to it via the signal module and gracefully shutdown:
loop = asyncio.get_event_loop()
loop.call_soon_threadsafe(loop.stop)
sys.exit(0)
The script than starts the apps in background and finishes.
Note that killall python3.7 will send SIGTERM signal to every python3.7 process!
When we need to restart we jus rune the following command:
os.execl("./restart.sh", 'restart.sh')
The first parameter is the path to the file and the second is the name of the process.
I'm trying to execute code on a remote machine (virtual), which runs a webserver with a single POST form, intended to do a simple ping. On the other side is the following script (part of it):
exec("/bin/ping -c 4 ".$_POST["addr"]);
"addr" is where the data entered in the POST form goes. So basically it calls /bin/ping and appends whatever data I enter. The question is how can I leverage this to get a shell? I think that since the ping command runs with root privileges it should be fairly easy but I'm still new to this game and couldn't find any useful info on how to do this. Help will be very much appreciated :)
I'm trying to execute a child_process synchronously in node.js (Yes, I know this is bad, I have a good reason) and retrieve any output on stdout, but I can't quite figure out how...
I found this SO post: node.js execute system command synchronously that describes how to use a library (node-ffi) to execute the command, and this works great, but the only thing I'm able to get is the process exit code. Any data the command executes is sent directly to stdout -- how do I capture this?
> run('whoami')
username
0
in otherwords, username is echo'd to stdout, the result of run is 0.
I'd much rather figure out how to read stdout
So I have a solution working, but don't exactly like it... Just posting here for reference:
I'm using the node-ffi library referenced in the other SO post. I have a function that:
takes in a given command
appends >> run-sync-output
executes it
reads run-sync-output synchronously and stores the result
deletes this tmp file
returns result
There's an obvious issue where if the user doesn't have write access to the current directory, it will fail. Plus, it's just wasted effort. :-/
I have built a node.js module that solves this exact problem. Check it out :)
exec-plan
Update
The above module solves your original problem, because it allows for the synchronous chaining of child processes. Each link in the chain gets the stdout from the previous process in the chain.
I had a similar problem and I ended up writing a node extension for this. You can check out the git repository. It's open source and free and all that good stuff !
https://github.com/aponxi/npm-execxi
ExecXI is a node extension written in C++ to execute shell commands
one by one, outputting the command's output to the console in
real-time. Optional chained, and unchained ways are present; meaning
that you can choose to stop the script after a command fails
(chained), or you can continue as if nothing has happened !
Usage instructions are in the ReadMe file. Feel free to make pull requests or submit issues!
However it doesn't return the stdout yet... Well, I just released it today. Maybe we can build on it.
Anyway, I thought it was worth to mention it. I also posted this to a similar question: node.js execute system command synchronously
Since Node version v0.11.12, there is a child_process.execSync function for this.
Other than writing code a little diferent, there's actually no reason to do anything synched.
What don't you like about this? (docs)
var exec = require('child_process').exec;
exec('whoami', function (error, username) {
console.log('stdout: %s', username);
continueWithYourCode();
});