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Exit to while read

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# 8  
Old 11-11-2017
You haven't said what shell or operating system you're using. When I try the following script on a macBook Pro running macOS Sierra version 10.12.6 using ksh (version sh (AT&T Research) 93u+ 2012-08-01), I think it does what you want:
Code:
#!/bin/ksh
logfile=/tmp/test.log

func_monitoring() {
	printf '	Monitoring "%s"...\n' "$logfile"
	tail -f -n0 "$logfile" | 
	while read line
	do	printf '(func_monitoring read) %s\n' "$line"
		if [ "$line" = "pattern1" ]
		then	echo "patter1"
			return
		elif [ "$line" = "pattern2" ]
		then	echo "patter2"
			return
		fi
	done
}

func_menu() {
	while :
	do	clear
		printf "%s

			[1] Monitor the log

			[2] Exit


		Please Select Number [1-2]: " "$directions"

		directions=
		read -n1 yourch
		case $yourch in
		(1)	echo
			func_monitoring
			sleep 5;;
		(2)	clear
			echo Goodbye.
			exit 0;;
		(*)	directions='	Please select choice 1 or 2';;
		esac
	done
}
func_menu

it loops on the read in func_monitoring until a line is found that matches one of the two given strings. Then it prints a line and sleeps for 5 seconds. And then it returns to the menu display loop in func_menu.

When I try running the same code with bash (version GNU bash, version 3.2.57(1)-release (x86_64-apple-darwin16)) func_monitoring doesn't return to func_menu until it has read another line from your log file after finding a matching line (which I assume is why you're trying to kill the tail after finding a matching line).
This User Gave Thanks to Don Cragun For This Post:
lxdorney
# 9  
Old 11-12-2017
Wouldn't a case statement lend itself to evaluating the patterns in func_monitoring?
# 10  
Old 11-12-2017
Quote:
Originally Posted by RudiC
Wouldn't a case statement lend itself to evaluating the patterns in func_monitoring?
Yes. Using case patterns to match lines instead of using test's = operator would help if matching words on a line instead of looking for exact matches to a complete line is the desired goal.

But, making that change won't affect when tail terminates after the remainder of the pipeline terminates. For that we need to know what shell is being used and what version of that shell. I've shown a way to make it work with the Korn shell if I understand what lxdorney is trying to do correctly (and I'm not sure that I do). I believe that some versions of bash have an option to make the last process in a pipeline the process group leader of that pipeline (like ksh does) instead of the first process in the pipeline (like bash does by default), but I'm not going to try to research ways to do this in every possible shell when lxdorney could tell us what version of what shell is being used so we could reasonably limit our research.
# 11  
Old 11-12-2017
OS: centos 6.9
# 12  
Old 11-12-2017
Quote:
Originally Posted by lxdorney
OS: centos 6.9
Great. Now we know what operating system you're using.

But, since i neither use nor have access to a system that is running that OS, I still don't know what what shell is installed as /bin/sh on your system. What output do you get when you run the command sh --version?

What output do you get when you run the command bash --version? And, what output do you get when you run the command bash --lastpipe?

Do you have ksh installed on your system? What output do you get from the command ksh --version?

I provided a script in post #8 in this thread. Did you try installing it and executing it with ksh? If so, what happened? If not, why not?
# 13  
Old 11-12-2017
Code:
GNU bash, version 4.1.2(2)-release-(x86_64-redhat-linux-gnu)
Usage:  sh [GNU long option] [option] ...
        sh [GNU long option] [option] script-file ...
GNU long options:
        --debug
        --debugger
        --dump-po-strings
        --dump-strings
        --help
        --init-file
        --login
        --noediting
        --noprofile
        --norc
        --posix
        --protected
        --rcfile
        --rpm-requires
        --restricted
        --verbose
        --version
Shell options:
        -irsD or -c command or -O shopt_option          (invocation only)
        -abefhkmnptuvxBCHP or -o option
Type `sh -c "help set"' for more information about shell options.
Type `sh -c help' for more information about shell builtin commands.

---------- Post updated at 09:07 PM ---------- Previous update was at 09:02 PM ----------

I tried the script and execute this command to append the test.log
Code:
echo "pattern1" >>/tmp/test.log

but same is not go back to menu and when try to execute again the
Code:
echo "pattern2" >>/tmp/test.log

, then is back to the menu.


Sorry my apologies, 2 append with any patterns, "pattern1 or pattern2" is working, I will edit my reply
Last edited by lxdorney; 11-12-2017 at 10:32 PM..
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