I am trying to execute a remote command for one of my scripts. I have to run this script across many servers. so i will put it in a script. What I am trying to do is
ssh root#10.158.42.12 nohup perl /script/myscript.pl 06/04/2014 60 &
The script runs just fine but there is an info message which is displayed whenever you try to login . The one many of you would be familiar with ..
|-----------------------------------------------------------------|
| This system is for the use of authorized users only. |
| Individuals using this computer system without authority, or in |
Due to this the script execution is haulted unless an enter is pressed. I want to put the script in a cronjob for automatic execution, so i dont need to see this info message.
Here's my theory:
Your command doesn't run the program in the background on the server. It runs runs the program in the foreground on the server, and then you background ssh.
Since ssh runs in the background, you are immediately returned to your prompt.
Milliseconds later, ssh overwrites your prompt with this message and runs the command.
You are now looking at the ssh message and no prompt.
You hit press enter, which causes the prompt to be redrawn on the next line.
This leads you to believe ssh was actually waiting for you to press enter. In reality, the command was already run, and bash was ready for new commands, just obscured by ssh noise.
How to test:
If I'm right, pressing Ctrl+L instead of Enter will clear the screen and show the bash prompt. (assuming you don't use bash's vi mode).
If I'm not, Ctrl+L will instead either do nothing, print the ssh message again or just write ^L to the screen.
How to fix if I'm right:
ssh -f root#10.158.42.12 'nohup perl /script/myscript.pl 06/04/2014 60 &' 2> /dev/null
Related
I have a game server running in an xterm window.
Once daily I'd like to send a warning message to any players followed after a delay by the stop command to the program inside the xterm window from a script running on a schedule. This causes the cleanup and save functions to run automatically.
Once the program shuts down I can bring it back up easily but I don't know how to send the warning and stop commands first.
Typed directly into xterm the commands are:
broadcast Reboot in 2 minutes
(followed by a 2 minute wait and then simply):
stop
no / or other characters required.
Any help?
Do you also need to type something from the xterm itself (from time to time) or do you want your server to be fully driven from external commands?
Is your program line-oriented? You may first try something like:
mkfifo /tmp/f
tail -f /tmp/f | myprogram
and then try to send commands to your program (from another xterm) with
echo "mycommand" > /tmp/f
You may also consider using netcat for turning your program to a server:
Turn simple C program into server using netcat
http://lifehacker.com/202271/roll-your-own-servers-with-netcat
http://nc110.sourceforge.net/
Then you could write a shell script for sending the required commands to your "server".
If you know a little about C programming; I remember having once hacked the script program (which was very easy to do: code is short) in order to launch another program but to read commands from a FIFO file (then again a shell script would be easy to write for driving your program).
Something you might try is running your program inside a screen session.
You can then send commands to the session from cron that will be just
as if you typed them.
In your xterm, before launching the program do:
screen -S myscreen bash
(or you can even replace bash by your program). Then from your cron
screen -S myscreen -X stuff 'broadcast Reboot in 2 minutes\n'
sleep 120
screen -S myscreen -X stuff 'stop\n'
will enter that text. You can exit the session using screen -S myscreen -X quit
or by typing ctrl-a \.
screen is intended to be transparent. To easily see you are inside screen, you can
configure a permanent status bar at the bottom of your xterm:
echo 'hardstatus alwayslastline' >~/.screenrc
Now when you run screen you should see a reverse video bottom line. Depending
on your OS it may be empty.
What's the best way to run this shell script where I need to create an output log at the same time run it in the background? The catch is, I need to input a couple of parameters then enter a password.
For example I execute the shell script like so:
-bash-4.3$ ./tst.sh param1 param2 >> tst.log
Password for user mas:
I need to pass in (2) parameters, then prompted for a password:
./tsh.sh <param1> <param2>
This will work, but I have to keep the session open and I want it so it goes to the background or something similar where it will continue to run if my connection to the host fails..
If you want to run something that will survive if your connection fails you should run it in a screen or tmux session. You can use those to create sessions that you can disconnect from and reconnect to, and many other really cool things once you start really getting into them.
So if you ssh in and then run screen you'll still be at a bash prompt, but if you run a command then press ^a^d you will detach from that session. Everything running inside screen will keep going, and you'll be able to reconnect with screen -x later. You can have many screen sessions at the same time too, use screen -ls to see which are running then you can use screen -x <id> to reconnect to a particular one.
This hopefully should be an easy question to answer. I am attempting to have mumble-ruby run automatically I have everything up and running except after running this simple script it runs but ends. In short:
Running this from terminal I get "Press enter to terminate script" and it works.
Running this via a cronjob runs the script but ends it and runs cli.disconnect (I assume).
I want the below script to run automatically via a cronjob at a specified time and not end until the server shuts down.
#!/usr/bin/env ruby
require 'mumble-ruby'
cli = Mumble::Client.new('IP Address', Port, 'MusicBot', 'Password')
cli.connect
sleep(1)
cli.join_channel(5)
stream = cli.stream_raw_audio('/tmp/mumble.fifo')
stream.volume = 2.7
print 'Press enter to terminate script';
gets
cli.disconnect
Assuming you are on a Unix/Linux system, you can run it in a screen session. (This is a Unix command, not a scripting function.)
If you don't know what screen is, it's basically a "detachable" terminal session. You can open a screen session, run this script, and then detach from that screen session. That detached session will stay alive even after you log off, leaving your script running. (You can re-attach to that screen session later if you want to shut it down manually.)
screen is pretty neat, and every developer on Unix/Linux should be aware of it.
How to do this without reading any docs:
open a terminal session on the server that will run the script
run screen - you will now be in a new shell prompt in a new screen session
run your script
type ctrl-a then d (without ctrl; the "d" is for "detach") to detach from the screen (but still leave it running)
Now you're back in your first shell. Your script is still alive in your screen session. You can disconnect and the screen session will keep on trucking.
Do you want to get back into that screen and shut the app down manually? Easy! Run screen -r (for "reattach"). To kill the screen session, just reattach and exit the shell.
You can have multiple screen sessions running concurrently, too. (If there is more than one screen running, you'll need to provide an argument to screen -r.)
Check out some screen docs!
Here's a screen howto. Search "gnu screen howto" for many more.
Lots of ways to skin this cat... :)
My thought was to take your script (call it foo) and remove the last 3 lines. In your /etc/rc.d/rc.local file (NOTE: this applies to Ubuntu and Fedora, not sure what you're running - but it has something similar) you'd add nohup /path_to_foo/foo 2>&1 > /dev/null& to the end of the file so that it runs in the background. You can also run that command right at a terminal if you just want to run it and have it running. You have to make sure that foo is made executable with chmod +x /path_to_foo/foo.
Use an infinite loop. Try:
while running do
sleep(3600)
end
You can use exit to terminate when you need to. This will run the loop once an hour so it doesnt eat up processing time. An infinite loop before your disconnect method will prevent it from being called until the server shuts down.
I logged in to a remote server via ssh and started a php script. Appereantly, it will take 17 hours to complete, is there a way to break the connection but the keep the script executing? I didn't make any output redirection, so I am seeing all the output.
Can you stop the process right now? If so, launch screen, start the process and detach screen using ctrl-a then ctrl-d. Use screen -r to retrieve the session later.
This should be available in most distros, failing that, a package will definitely be available for you.
ctrl + z
will pause it. Than type
bg
to send it to background. Write down the PID of the process for later usage ;)
EDIT: I forgot, you have to execute
disown -$PID
where $PID is the pid of your process
after that, and the process will not be killed after you close the terminal.
you described it's important to protect script continuation. Unfortunately I don't know, you make any interaction with script and script is made by you.
continuation protects 'screen' command. your connection will break, but screen protect pseudo terminal, you can reconnect to this later, see man.
if you don't need operators interaction with script, you simply can put script to background at the start, and log complete output into log file. Simply use command:
nohup /where/is/your.script.php >output.log 2&>1 &
>output.log will redirect output into log file, 2&>1 will append error stream into output, effectively into log file. last & will put command into background. Notice, nohup command will detach process from terminal group.
At now you can safely exit from ssh shell. Because your script is out of terminal group, then it won't be killed. It will be rejoined from your shell process, into system INIT process. It is unix like system behavior. Complete output you can monitor using command
tail -f output.log #allways breakable by ^C, it is only watching
Using this method you do not need use ^Z , bg etc shell tricks for putting command to the background.
Notice, using redirection to nohup command is preferred. Otherwise nohup will auto redirect all outputs for you to nohup.out file in the current directory.
You can use screen.
my bash script reads in a few variables and then runs airodump on my home network. I would like to keep the window with airodump running and open some new terminals to run other commands for network discovery while the airodump screen is open (so i can see the results).
right now what i have looks like this (edited for brevity):
#!/bin/bash
read -p "Enter the channel: $channel"
airomon-ng start wlan0 $channel,$channel
airodump-ng -c $channel,$channel mon0 &&
terminator -e netstat -ax &&
terminator -e nmap 192.168.1.1
the first command that uses the whole terminal (airodump) starts up fine and i can see the network, but then it just stays on that screen. If i ctrl+c then it goes back to prompt but i can see the error : Usage: terminator [options] error no such option
i want the netstat and nmap commands to appear and stay in their own terminal windows, how can i do this?
The terminal window is generated by a separate program from the command running inside. Try one of these variations:
xterm -e airomon-start wlan0 "$channel","$channel" &
gnome-terminal -x airomon-start wlan0 "$channel","$channel" &
konsole -e airomon-start wlan0 "$channel","$channel" &
Pick the command that invokes the terminal program you like. You'll have to do this for every command that you want run in its own window. Also, you need to use a single & at the end of each such command line -- not a double && -- those do totally different things. And the last line of your script should be just
wait
that makes it not exit out from under all the terminals, possibly causing them all to die.
Obligatory tangential shell-scripting nitpick: ALWAYS put shell variable uses inside double quotes, unless you know for a fact that you need word-splitting to happen on a particular use.
If the script is running in the foreground in the terminal, then it will pause while an interactive command is using the terminal. You could change the script to run airodump in a new terminal as well, or you could run the background commands before you start airodump (maybe after sleeping, if you're concerned they won't work right if run first?)