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[BASH] Script to manage background scripts (running, finished, exit code)

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Top Forums Shell Programming and Scripting [BASH] Script to manage background scripts (running, finished, exit code)
# 15  
Old 10-16-2014
Quote:
Originally Posted by Chubler_XL
First time I've seen this approach does this actually signal the running process in any way?

Do you know how portable this zero signal is?
Quote:
Originally Posted by Corona688
kill is faster than ps? I think they're both externals..
The POSIX Standards and the Single UNIX Specifications specify that the function call:
Code:
kill(pid, 0)

shall not actually send a signal but shall perform normai error checking. So, if the process ID is valid and you have permission to send that process a signal, it will return 0; otherwise, it will return -1 with errno set to ESRCH if the process doesn't exist or EPERM if you don't have permission to send a signal to your child. The standards also require that the kill utility behave as though kill(pid, 0) were called when you invoke the command kill -0 pid. All UNIX Systems do this; I can't speak to whether or not Linux systems' kill utilities and system calls conform to these requirements.

As Chubler_XL said, any shell that handles job control that I've seen has kill as a shell built-in. Even if it doesn't, ps usually needs to do a lot more poking around in kernel memory than kill does; so it should be faster.
This User Gave Thanks to Don Cragun For This Post:
Corona688
# 16  
Old 10-17-2014
Hi.

Obviously a lot of work and thought has been put into this. As far as I know, the requirements:
Code:
    * 'any' amount of scripts passed,
    * provides a limiter, so only X scripts are running simultaneously
    * Prints the status code of each of the scripts ran

can be accomplished through utilities xargs and GNU parallel. Here's an example of a number of script names in a data file that will be "executed". First singly (not in parallel), then at most n=2 at a time. The script that "runs" the script name is run with ksh so that the number of processes can be more easily seen.
Code:
#!/usr/bin/env bash

# @(#) s1	Demonstrate parallel execution of scripts, GNU parallel.

# Utility functions: print-as-echo, print-line-with-visual-space, debug.
# export PATH="/usr/local/bin:/usr/bin:/bin"
LC_ALL=C ; LANG=C ; export LC_ALL LANG
pe() { for _i;do printf "%s" "$_i";done; printf "\n"; }
pl() { pe;pe "-----" ;pe "$*"; }
db() { ( printf " db, ";for _i;do printf "%s" "$_i";done;printf "\n" ) >&2 ; }
db() { : ; }
C=$HOME/bin/context && [ -f $C ] && $C parallel

FILE=${1-data1}

pl " Input data file, names of scripts, $FILE:"
cat $FILE

pl " Master execution script s0:"
cat s0

pl " Results:"
parallel ./s0 < $FILE

pl " Results, limitation of 2 scripts simultaneously:"
parallel --jobs 2 ./s0 < $FILE

exit 0

producing:
Code:
$ ./s1

Environment: LC_ALL = C, LANG = C
(Versions displayed with local utility "version")
OS, ker|rel, machine: Linux, 2.6.26-2-amd64, x86_64
Distribution        : Debian 5.0.8 (lenny, workstation) 
bash GNU bash 3.2.39
parallel GNU parallel 20111122

-----
 Input data file, names of scripts, data1:
foo
bar
baz
qux
quux
corge

-----
 Master execution script s0:
#!/usr/bin/env ksh

# @(#) s0	Demonstrate script to execute a script from argument 1.

printf " $0: would have executed script %s here, process $$\n" $1
printf " exit status of script %s is %d\n" $1 $?
printf " Current processes:\n"
ps
sleep 1

exit 0

-----
 Results:
 ./s0: would have executed script foo here, process 12774
 exit status of script foo is 0
 Current processes:
  PID TTY          TIME CMD
 3451 pts/13   00:00:01 bash
12670 pts/13   00:00:00 bash
12734 pts/13   00:00:00 parallel
12774 pts/13   00:00:00 ksh
12775 pts/13   00:00:00 ps
 ./s0: would have executed script bar here, process 12776
 exit status of script bar is 0
 Current processes:
  PID TTY          TIME CMD
 3451 pts/13   00:00:01 bash
12670 pts/13   00:00:00 bash
12734 pts/13   00:00:00 parallel
12776 pts/13   00:00:00 ksh
12777 pts/13   00:00:00 ps
 ./s0: would have executed script baz here, process 12781
 exit status of script baz is 0
 Current processes:
  PID TTY          TIME CMD
 3451 pts/13   00:00:01 bash
12670 pts/13   00:00:00 bash
12734 pts/13   00:00:00 parallel
12781 pts/13   00:00:00 ksh
12782 pts/13   00:00:00 ps
 ./s0: would have executed script qux here, process 12783
 exit status of script qux is 0
 Current processes:
  PID TTY          TIME CMD
 3451 pts/13   00:00:01 bash
12670 pts/13   00:00:00 bash
12734 pts/13   00:00:00 parallel
12783 pts/13   00:00:00 ksh
12784 pts/13   00:00:00 ps
 ./s0: would have executed script quux here, process 12785
 exit status of script quux is 0
 Current processes:
  PID TTY          TIME CMD
 3451 pts/13   00:00:01 bash
12670 pts/13   00:00:00 bash
12734 pts/13   00:00:00 parallel
12785 pts/13   00:00:00 ksh
12786 pts/13   00:00:00 ps
 ./s0: would have executed script corge here, process 12787
 exit status of script corge is 0
 Current processes:
  PID TTY          TIME CMD
 3451 pts/13   00:00:01 bash
12670 pts/13   00:00:00 bash
12734 pts/13   00:00:00 parallel
12787 pts/13   00:00:00 ksh
12788 pts/13   00:00:00 ps

-----
 Results, limitation of 2 scripts simultaneously:
 ./s0: would have executed script foo here, process 12815
 exit status of script foo is 0
 Current processes:
  PID TTY          TIME CMD
 3451 pts/13   00:00:01 bash
12670 pts/13   00:00:00 bash
12789 pts/13   00:00:00 parallel
12815 pts/13   00:00:00 ksh
12816 pts/13   00:00:00 ps
12817 pts/13   00:00:00 ksh
12818 pts/13   00:00:00 ps
 ./s0: would have executed script bar here, process 12817
 exit status of script bar is 0
 Current processes:
  PID TTY          TIME CMD
 3451 pts/13   00:00:01 bash
12670 pts/13   00:00:00 bash
12789 pts/13   00:00:00 parallel
12815 pts/13   00:00:00 ksh
12817 pts/13   00:00:00 ksh
12818 pts/13   00:00:00 ps
 ./s0: would have executed script baz here, process 12822
 exit status of script baz is 0
 Current processes:
  PID TTY          TIME CMD
 3451 pts/13   00:00:01 bash
12670 pts/13   00:00:00 bash
12789 pts/13   00:00:00 parallel
12822 pts/13   00:00:00 ksh
12823 pts/13   00:00:00 ps
12824 pts/13   00:00:00 ksh
12825 pts/13   00:00:00 ps
 ./s0: would have executed script qux here, process 12824
 exit status of script qux is 0
 Current processes:
  PID TTY          TIME CMD
 3451 pts/13   00:00:01 bash
12670 pts/13   00:00:00 bash
12789 pts/13   00:00:00 parallel
12822 pts/13   00:00:00 ksh
12824 pts/13   00:00:00 ksh
12825 pts/13   00:00:00 ps
 ./s0: would have executed script corge here, process 12828
 exit status of script corge is 0
 Current processes:
  PID TTY          TIME CMD
 3451 pts/13   00:00:01 bash
12670 pts/13   00:00:00 bash
12789 pts/13   00:00:00 parallel
12826 pts/13   00:00:00 ksh
12827 pts/13   00:00:00 ps
12828 pts/13   00:00:00 ksh
12829 pts/13   00:00:00 ps
 ./s0: would have executed script quux here, process 12826
 exit status of script quux is 0
 Current processes:
  PID TTY          TIME CMD
 3451 pts/13   00:00:01 bash
12670 pts/13   00:00:00 bash
12789 pts/13   00:00:00 parallel
12826 pts/13   00:00:00 ksh
12827 pts/13   00:00:00 ps
12828 pts/13   00:00:00 ksh
12829 pts/13   00:00:00 ps

My apologies if I missed the point ... cheers, drl
This User Gave Thanks to drl For This Post:
sea
# 17  
Old 10-17-2014
His original script would have been able to run entire, complex, arbitrary shell statements in parallel. He wasn't testing it with them, but it could. This isn't necessarily a good thing, mind you -- leaves the door open for a lot of unintended problems.
# 18  
Old 10-18-2014
Thank you guys, i've tried to adapt some of your suggestions, /proc/$pid, kill -0 $pid, kill($pid,0) but none of them worked as expected.
The hint with a "single id number" was great, that way i just managed to make it even smaller than the previous example, with full functionality! Smilie

Screenshot shows how it returns the number of successfully executed scripts, when passed -c...

Below is the 'core' snippet, full script can be seen on https://github.com/sri-arjuna/tui/bl...er/bin/tui-psm
And it is part of: https://github.com/sri-arjuna/tui.git

Hope you like it, and thank you for your help!
Code:
#
#	Variable presets
#
	script_name=( "${@}" )		# Contains all files
	MAX=${#script_name[@]}		# Max amount of scripts
	script_status=( $(for s in "${script_name[@]}";do echo "3";done) )		# Status with same counter of that file	: done(0) failed(1) running(2) todo(3)
	script_pid=()			# PID with the same counter of that file

	# Counters
	RUN=0			# How many scripts are currently running
#
#	Display & Action
#
	while [[ $DONE -lt $MAX ]]
	do	# Loop the menu
		C=0
		DONE=0			# How many scripts are 'done' (regardless of status)
		GOOD=0			# How many scripts ended succesffully
		if ! $QUIET
		then	clear
			tui-header "$TITLE ($script_version)" "$(date +'%F %T')"
			tui-title "Status"
		fi
		
		while [[ $C -lt $MAX ]]
		do	# Vars
			STATUS="${script_status[$C]}"	# Current status
			RET_FILE="$TEMP/$(basename ${script_name[$C]}).ret"
		
			# Do action according to current status
			case $STATUS in
			2)	# IS PID still available?
				pid=${script_pid[$C]} 
				if [[ ! -z "$(echo $pid)" ]]
				then	#if ! ls /proc/${script_pid[$C]}
					if ! ps $pid > /dev/zero
					#if kill -0 $pid  2>&/dev/null
					then	# Its finished
						read RET < "$RET_FILE"
						[[ -z "$RET" ]] && RET=1
						script_status[$C]=$RET
						((RUN--))
					fi
				else 	tui-status 1 "This should not happen, empty pid while running"
				fi
				;;
			3)	# Its TODO, can we start it?
				if [[ $RUN -lt $LIMIT ]] || [[ $LIMIT -eq 0 ]]
				then 	script_status[$C]=2
					STATUS=2
					((RUN++))
					script="${script_name[$C]}"
					[[ [./] = "${script:0:1}" ]] && PRE="" || PRE="./"
					cmd="\"${PRE}$script\" ; echo \$? > \"$RET_FILE\""
					touch "$RET_FILE"
					( eval "$cmd" ) &
					script_pid[$C]=$!
				fi
				;;
			*)	((DONE++))
				[[ $STATUS -eq 0 ]] && ((GOOD++))
				;;
			esac

			# Display latest status
			if ! $QUIET
			then	case $STATUS in
				0|1)	tui-status $STATUS "Finished ${script_name[$C]}"  ;;
				2)	tui-status $STATUS "Running ${script_name[$C]}" "${script_pid[$C]}" ;;
				3)	tui-status $STATUS "Waiting ${script_name[$C]}" ;;
				127)	tui-status 1 "Typo in script: \"${script_name[$C]}\""	;;
				*)	tui-status 1  "Invalid STATUS ($STATUS) on $C ${script_name[$C]}"	;;
				esac
			fi
			((C++))
		done
		
		if ! $QUIET
		then	tui-echo
			tui-title "Summary"
			tui-echo "Scripts completed:" "$DONE/$MAX"
			tui-echo "Currently running:" "$RUN/$LIMIT"
			tui-echo "Successfully executed:" "$GOOD"
			
			tui-echo
			tui-wait $WAIT "Wait for update..."
			echo
		else	sleep $WAIT
		fi
	done

EDIT:
I just think it looks cool, thank you guys!
[BASH] Script to manage background scripts (running, finished, exit code)-tui-bg-scripts-working2jpg
[BASH] Script to manage background scripts (running, finished, exit code)-tui-bg-scripts-progressjpg
Last edited by sea; 01-29-2015 at 02:41 PM..
This User Gave Thanks to sea For This Post:
Corona688
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