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Old 02-15-2007, 01:34 PM   #1
riotxix
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Adding commands when it's too late


Hi,

sometimes I run a script or program which takes a while to run (like compiling something). Half through, I realise that I would like to run a command afterwards (say, reboot or beep). Had I realised earlier, I could have done

cmd1 ; reboot

But if it's already running, is there anyway to tag on subsequent commands? I mean, it is possible to pause it with a CTRL-Z in the bash shell.

If not, I may try writing an app that I can run in the CTRL-Z space, like checkApp cmd1 -[cmd2 cmd3] & ( ; fg 1), which greps ps -ef to see if cmd1 is still running, and if not run cmd2, cmd3 etc. Perhaps one exists though?

Does something like this already exist, or is there a way of tagging on subsequent commands?

Thank you for your time.

---EDIT
by Jojo http://www.votelinux.com/tips/144-Re...ram-is-running
Here is a little bash script which will monitor the status of any process. Just call it with the processname (or a part of it) and it will loop endlessly unless the given process has quit.
This is very useful to monitor the status of daemons on a server

#!/bin/bash

while ps ax | grep -v -e grep -e [scriptFileName] | grep -q $1 ; do
echo "Programm $1 running"
sleep 1
done
------

Last edited by riotxix; 02-15-2007 at 04:31 PM.
 
Old 02-15-2007, 02:09 PM   #2
colucix
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A simple way to do this, is:
1) Stop the command execution with Ctrl-Z
2) Put it in background with command bg
3) Type the following command and press enter
Code:
wait $! && echo done
The wait command is a shell builtin that waits for a process to accomplish its task and return the exit command of that process (see man bash for details). The $! means "last background process". So, after you have put the command in background you wait for its completion and when the command has successfully completed the command after && is executed. More difficult to explain than to do!
 
Old 02-15-2007, 02:11 PM   #3
Samoth
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Isn't that "!$"?

because I know that if I do
Code:
echo x >> foo && vi !$
I will edit foo.

Also, I can run a command, then halfway into it just type the next command and push Return and it will run the second command when the other one is finished.

Last edited by Samoth; 02-15-2007 at 02:12 PM.
 
Old 02-15-2007, 02:14 PM   #4
colucix
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It is a really different thing:
$! takes the "last background job"
!$ takes the "last word of the previous command"
As you can see they are totally unrelated.
 
Old 02-15-2007, 02:43 PM   #5
gnashley
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Oh, this is juicy stuff! I knew about using $! but not the other one. Perhaps one of you can help with a related question. How do you 'fish' for variables deaclared before the last command, or before the current process?
What I mean is, I start a process like this:

VAR=SomeValue program-name

program-name is a BASH script of course. How can find out what was given before
program-name on the command-line?


Here's the way I use $!

Code:
rotdash2()
{
  p=$1
  while [ -d /proc/$p ]
  do
    echo -en '\E[32;40m/\E[B' ; sleep .05
    echo -en '\E[32;40m-\E[B' ; sleep .05
    echo -en '\E[32;40m\\E[B' ; sleep .05
    echo -en '\E[32;40m|\E[B' ; sleep .05
    echo -en '\E[32;42mS' ; tput sgr0 ; sleep .2
  done
}

prog-name &
rotdash2 $!
That makes a nice little CLI progress-bar (green) with a rotating star-looking cursor

Last edited by gnashley; 02-17-2007 at 07:25 AM.
 
Old 02-15-2007, 08:36 PM   #6
Samoth
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Ah yes, my mistake.

That looks interesting, gnashley, but how exactly do you call it? Does that program take the place of $!?
 
Old 02-16-2007, 01:54 AM   #7
gnashley
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prog-name is the program that gets its' progress tracked with a bar. It must be backgrounded like: 'prog-name &'. Then when calling the function rotdash2, the &! makes it attach the last background process to the rotdash2 program. BTW, that code is mostly credited to Klaus Knopper -I just had to do some minor changes in the escape characters or something for use with BASH. The original code was for ash-knoppix.
 
Old 02-16-2007, 10:35 AM   #8
Four
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How does it know how far the program is into? Also I see a strange symbols at the '\E[32;40m/' last character of each of those statments.

Thanks
 
Old 02-17-2007, 07:27 AM   #9
gnashley
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$! is the process id fed to p=$1
while [ -d /proc/$p ] tracks the exisitng of the process
all the echoes can be replaced by a simple sleep if you just want poll
to see if the process is running. Be sure to sleep or do something in the loop or you have a run-away process.

Those funny characters are BS (back-spaces). Whats the escape sequence for that? Wait, I've been playing with that, look at the edited code above.
echo -e \E[B backups one character. Using \E[b backs up and repeats the prvious char?
 
Old 02-19-2007, 08:11 AM   #10
bigearsbilly
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I don't get it !?!?!
if you type in a command after something has started running it will run afterwards anyway.

the keyboard doesn't turn off when a command runs.
 
  


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