another odd command usage

citrus · 05-11-2004, 01:57 PM

ok i have a program called sc_trans_linux

heres what i need bear with me

the program runs at system start

but i need the PID of the program

this command

kill -WINCH "PID"
changes the song (its a mp3 sourceclient for a shoutcast server)

at the start i want a basch script or something to find the pid of that program and export a variable for the PID so i can

kill -WINCH $variable

david_ross · 05-11-2004, 02:03 PM

What about:
PID=`ps -ef | grep sc_trans_linux | grep -v grep | awk {'print $2'}`

citrus · 05-11-2004, 02:09 PM

thanks that works
but what does the awk {'print 2'} fuction do

odviously it returns the pid number
but how does that work??

david_ross · 05-11-2004, 02:19 PM

To break it down:
Get all the system processes: ps -ef
Look for your program: grep sc_trans_linux
Ignore the grep itself: grep -v grep
Return column 2 of the line matched: awk {'print $2'}

The default field seperator for awk is white space but you can change it with --field-seperator if needed. The man page covers all the options in more detail.

citrus · 05-11-2004, 02:27 PM

thanks

how would i save that variable so i can use it in any terminal window??

david_ross · 05-11-2004, 02:29 PM

You won't be able to use it in any terminal. You could write it to a file which can then be intereigate from another terminal

Tinkster · 05-11-2004, 02:36 PM

or make that line an alias if you're planning on
using it on a regular basis ;)

Cheers,
Tink

citrus · 05-11-2004, 02:42 PM

ok

so lets say i saved in a file the PID that is

so now i have a file called number

pico number
returns the PID number just fine

how can i kill -WINCH /number

or how can i make a variable of that number from the text file

kinda like NUM=/number

citrus · 05-11-2004, 02:46 PM

i could make an alias

but how? cuz i could

alias go="kill -WINCH $PID"

but..
since i want to run that pid prosses at start the variable wont work when i log in to a term

Tinkster · 05-11-2004, 02:46 PM

Quote:

Originally posted by citrus
how can i kill -WINCH /number
or how can i make a variable of that number from the text file

Why don't you make
alias sc_kill="kill -WINCH `ps -ef | grep sc_trans_linux | grep -v grep | awk {'print $2'}`"
? :)

Just add that alias definition to your ~/.bashrc (or appropriate file).

No need to get a file involved, specially considering that
the PID will be different next time you run sc_tans_linux.

Cheers,
Tink

citrus · 05-11-2004, 02:51 PM

k i will try that

Tinkster · 05-11-2004, 02:55 PM

Quote:

almost quote from citrus
Will that alias be available in every terminal?

If it's defined in a file that the shell sources on
start, yes. It just depends on how you invoke
bash into which file you should stick it.

.bash_rc
or
.bash_profile

If in doubt, set-up a .bashrc and create a .bash_profile
that just sources .bashrc

Cheers,
Tink

citrus · 05-11-2004, 03:07 PM

i am unsure what my .bashrc file is named or what to name it

~/.bashrc doesn't work
i am using slackware 9.1

edit::
i will try .bash_profile

jschiwal · 05-11-2004, 03:26 PM

You probably want to use .bash_profile for setting up aliases and functions. It is sourced once when you log in. .bashrc is souced when everytime you start a new shell.
Look in the man page for bash for all the details. Look at which files are sourced under which circumstance. Some files may be sourced by more than one shell also. That may be something to take into consideration.
If you have different accounts you login to, examine where your system sets its functions or aliases and add it there.