Updating value from new last line of tempfile

05-31-2015

Registered User

1,416, 266

Join Date: Sep 2013

Last Activity: 13 January 2021, 9:37 AM EST

Location: Swissh

Posts: 1,416

Thanks Given: 328

Thanked 266 Times in 239 Posts

Updating value from new last line of tempfile

Heyas

A variable within a loop doesnt get updated - eventhough the 'inputfile' changes.

I have a tempfile ($TMP.playstatus), which contains this data:

Code:

   0.11 M-A:  0.000 fd=   0 aq=    4KB vq=    0KB sq=    0B f=0/0   
   0.14 M-A:  0.000 fd=   0 aq=    4KB vq=    0KB sq=    0B f=0/0   
   0.16 M-A:  0.000 fd=   0 aq=    4KB vq=    0KB sq=    0B f=0/0   
   0.19 M-A:  0.000 fd=   0 aq=    4KB vq=    0KB sq=    0B f=0/0   
   0.23 M-A:  0.000 fd=   0 aq=    4KB vq=    0KB sq=    0B f=0/0   
   0.26 M-A:  0.000 fd=   0 aq=    4KB vq=    0KB sq=    0B f=0/0   
   0.28 M-A:  0.000 fd=   0 aq=    4KB vq=    0KB sq=    0B f=0/0   
   0.31 M-A:  0.000 fd=   0 aq=    4KB vq=    0KB sq=    0B f=0/0   
   0.35 M-A:  0.000 fd=   0 aq=    4KB vq=    0KB sq=    0B f=0/0

Where constantly a new line is appended.

I have this semi working:

Code:

	$SHELL "$TMP" &
	PID=$!
	sleep 1.4
	while ps $PID > /dev/zero
	do	CUR=$(tail -n1 $TMP.playstatus|awk '{print $1}')
# Deleted stuff
		echo tui-progress -bm "$PTS" -c "$CUR" "$CUR/$PT"
	done
	return

Deleted stuff (previous tries):

Code:

	#CUR=$($AWK '/M-A:/ {print $1}' $TMP.playstatus )
		#M-A:
		#echo "--> $CUR <--"
		#tail -n1 $TMP.playstatus
		#CUR=${CUR/\/*}
		#echo $CUR
		#$AWK '/M\-A:/ BEGINN {print $1}' $TMP.playstatus
	#	[ -z "$CUR" ] && \
	#		pkill ffplay && \
	#		tui-printf -S 1 "Cant read current playtime from $video, aborting..." && \
	#		tail -n1 $TMP.playstatus && \
	#		echo "---" && cat "$TMP" && \
	#		exit 1
		#exit
		#sh -x \

Regardless of what i try, the $CUR-value is read properly only the first time - so it seems to me, but afterwards it remains the same/doesnt change...
As in, beeing spamed with:

Code:

tui-progress -bm 3526 -c 0.04 0.04 /58:46
tui-progress -bm 3526 -c 0.04 0.04 /58:46
tui-progress -bm 3526 -c 0.04 0.04 /58:46

OR, almost the same:

Code:

tui-progress -bm 3526 -c 0.01 0.01/58:46
tui-progress -bm 3526 -c 0.01 0.01/58:46
tui-progress -bm 3526 -c 0.01 0.01/58:46

To my understanding the variable $CUR should be updated just before its echo'd within each loop.

Any advice/ideas please?
Thank you in advance

---------- Post updated at 11:14 ---------- Previous update was at 10:38 ----------

Maybe this different output helps:

Code:

		sleep 0.4
		while ps $PID > /dev/zero
		do 	CUR=$(tail -n1 "$STATUS"|$AWK '{print $1}')
			>"$STATUS"
			echo tui-progress -bm "$PTS" -c "$CUR" "$CUR/$PT"
			sleep 0.7
		done

Outputs as:

Code:

tui-progress -bm 3526 -c 0.01 0.01/58:46
tui-progress -bm 3526 -c  /58:46
tui-progress -bm 3526 -c  /58:46

Since the background job is told to redirect its output to $STATUS i thought after the cleaning the new lines would still be added.
Even when i DELETE the tempfile ($STATUS), it doesnt read a value while the files doesnt exist, and after... it jumps back to the first value (0.01), as if its 0.01 was even on the lowest line...

Last edited by sea; 05-31-2015 at 05:50 AM..

sea

View Public Profile for sea

Find all posts by sea

05-31-2015

Moderator

12,296, 3,792

Join Date: Nov 2008

Last Activity: 1 January 2021, 1:47 AM EST

Location: Amsterdam

Posts: 12,296

Thanks Given: 679

Thanked 3,792 Times in 3,282 Posts

In your first sample the sleep statement is missing, which is essential in this situation, otherwise the script checks uncontrolled number of time per second and unnecessarily strains the processor core...

In your 2nd sample the background job does not redirect its output to $STATUS.

Code:

>"$STATUS"

means truncate file "$STATUS", which empties the file, without deleting it.

---
Also, it is unusual to redirect output to /dev/zero, which is an input device, consider using /dev/null instead..

Last edited by Scrutinizer; 05-31-2015 at 04:19 PM..

Scrutinizer

View Public Profile for Scrutinizer

Find all posts by Scrutinizer

05-31-2015

Registered User

15,129, 5,008

Join Date: Jul 2012

Last Activity: 4 May 2020, 4:31 PM EDT

Location: Aachen, Germany

Posts: 15,129

Thanks Given: 735

Thanked 5,008 Times in 4,483 Posts

I can't reproduce that. Producing your temp file in background, and running your semi-working script snippet, I get

Code:

tui-progress -bm 3526 -c 0.109 0.109/0.01/58:46
tui-progress -bm 3526 -c 0.110 0.110/0.01/58:46
tui-progress -bm 3526 -c 0.111 0.111/0.01/58:46
tui-progress -bm 3526 -c 0.113 0.113/0.01/58:46
tui-progress -bm 3526 -c 0.114 0.114/0.01/58:46
tui-progress -bm 3526 -c 0.115 0.115/0.01/58:46
tui-progress -bm 3526 -c 0.116 0.116/0.01/58:46
tui-progress -bm 3526 -c 0.118 0.118/0.01/58:46
tui-progress -bm 3526 -c 0.119 0.119/0.01/58:46
etc.

What you should NOT do is redirect your stdout into your input file (reading from and redirecting into $STATUS), be it written by another process or not. If not, you'll erase it and then read only the lines back that have just been written by yourself. If written, you'll get a random mixup of lines by yourself and lines by the other process (what seems to be your sample output).

---------- Post updated at 21:54 ---------- Previous update was at 21:45 ----------

You can help me with a hint/trick: How did you get those <TAB> chars into the code text?

RudiC

View Public Profile for RudiC

Find all posts by RudiC

05-31-2015

Registered User

1,416, 266

Join Date: Sep 2013

Last Activity: 13 January 2021, 9:37 AM EST

Location: Swissh

Posts: 1,416

Thanks Given: 328

Thanked 266 Times in 239 Posts

@ The tab chars are in my code, copy paste preserves them usualy.

Thanks for your feedback, sadly i seem to apply this somehow wrong...

Function:

Code:

	PlayStatus() { # FILE
	# Prints the extra status play bar
	# Time as Progress, yay 
		# Vars
		PT=$(PlayTime)		# Get nice displayed playtime
		PTS=$(PlayTimeSecs)	# Get playtime as seconds
		[ "00" = "${PT:0:2}" ] && \
			PT="${PT/00:}"	# Cut off 'empty' leading hours
		PT="${PT/.*}"		# Cut off miliseconds
		STATUS="$TMP.playstatus"
		
		# Make required changes at the command file
		$SED s,'v quiet','hide_banner',g -i "$TMP"
		#$SED s,"||","1\>$STATUS 2\>$STATUS ||",g -i "$TMP"
		$SED s,"||"," 2\>$STATUS ||",g -i "$TMP"
		
		# Start job
		$SHELL "$TMP" &
		PID=$!
		sleep 0.7
		
		# TMP command
		tui-title "DIV"
		tui-cat $TMP
		tui-title "DIV"
		
		# Print information line
		while ps $PID > /dev/null
		do	CUR=$(tail -n1 "$STATUS"|awk '{print $1}')
			echo tui-progress -bm "$PTS" -c "$CUR" "$CUR/$PT"
			sleep 0.7
		done
		return
}

sh -x : output, still doesnt update the $CUR variable

Code:

+++ echo 00:58:46.03
++ str_work=00:58:46.03
++ base=46.03
++ mins=00:58
++ hours=00
++ H=0
++ M=3480
++ echo 46.03 3480 0
++ awk '{print int ($1 + $2 + $3)}'
+ PTS=3526
+ '[' 00 = 00 ']'
+ PT=58:46.03
+ PT=58:46
+ STATUS=/home/sea/.cache//vhs.tmp.playstatus
+ sed 's,v quiet,hide_banner,g' -i /home/sea/.cache//vhs.tmp
+ sed 's,||, 2\>/home/sea/.cache//vhs.tmp.playstatus ||,g' -i /home/sea/.cache//vhs.tmp
+ PID=6890
+ sleep 0.7
+ /bin/bash /home/sea/.cache//vhs.tmp
+ tui-title DIV
# |                                                      DIV                                                       | #
+ tui-cat /home/sea/.cache//vhs.tmp
# | ffplay -hide_banner -window_title "VHS (2.1.6) : Play audio File : joined_files.mp                             | #
# |                             3" -i "joined_files.mp3" -nodisp  2>/home/sea/.cache//vhs.tmp.playstatus || exit 1 | #
+ tui-title DIV
# |                                                      DIV                                                       | #
+ ps 6890
++ tail -n1 /home/sea/.cache//vhs.tmp.playstatus
++ awk '{print $1}'
+ CUR=0.01
+ echo tui-progress -bm 3526 -c 0.01 0.01/58:46
tui-progress -bm 3526 -c 0.01 0.01/58:46
+ sleep 0.7
+ ps 6890
++ tail -n1 /home/sea/.cache//vhs.tmp.playstatus
++ awk '{print $1}'
+ CUR=0.01
+ echo tui-progress -bm 3526 -c 0.01 0.01/58:46
tui-progress -bm 3526 -c 0.01 0.01/58:46
+ sleep 0.7
+ ps 6890
++ tail -n1 /home/sea/.cache//vhs.tmp.playstatus
++ awk '{print $1}'
+ CUR=0.01
+ echo tui-progress -bm 3526 -c 0.01 0.01/58:46
tui-progress -bm 3526 -c 0.01 0.01/58:46
+ sleep 0.7
^C

What am i doing wrong?

sea

View Public Profile for sea

Find all posts by sea

05-31-2015

Registered User

12,315, 4,560

Join Date: Jul 2012

Last Activity: 22 November 2019, 4:29 PM EST

Location: San Jose, CA, USA

Posts: 12,315

Thanks Given: 952

Thanked 4,560 Times in 3,818 Posts

Quote:

Originally Posted by RudiC

... ... ...

You can help me with a hint/trick: How did you get those <TAB> chars into the code text?

If you copy text containing <tab> characters, paste it into a message editing window on this site, and put CODE or ICODE tags around the pasted text, the <tab>s will be preserved.

Note, however, that if you copy text out of a vi editing window, you won't be copying <tab> characters because vi (and vim and other clones) display <space>s on the editing window instead of depending on currently set tab stops. But, if you cat the edited code to your screen and copy the cat output, the <tab>s will be preserved.

Don Cragun

View Public Profile for Don Cragun

Find all posts by Don Cragun

05-31-2015

Registered User

1,416, 266

Join Date: Sep 2013

Last Activity: 13 January 2021, 9:37 AM EST

Location: Swissh

Posts: 1,416

Thanks Given: 328

Thanked 266 Times in 239 Posts

OK, i guess we're getting closer.. while its playing in the background, i tried to read the status file manualy:

Code:

0 ~/.cache $ awk '/M-A/ {print $1}'  vhs.tmp.playstatus 
0.01

0 ~/.cache $ grep "M-A" vhs.tmp.playstatus 
 112.85 M-A:  0.000 fd=   0 aq=    4KB vq=    0KB sq=    0B f=0/0

But i just cant explaing the differende ?!

'Funny' thing is, with grep, it prints all the vars on a single line, and on the manual check, i see them prints over each other.
Inside the script function, the grep filtering causes a 'freeze', it keeps playing, but the code stucks at grep.

Eg:

Code:

while ps $PID > /dev/null
		do	#CUR=$(tail -n1 "$STATUS"|awk '{print $1}')
			#CUR=$($AWK '{print $1}' $STATUS | tail -n 1)
			list=$(awk '{print $1}' $STATUS)
			for l in $list;do CUR=$l;done
			#CUR=$(tail -n1 $STATUS|grep "M-A" )
			#CUR=$(tail -n1 $STATUS|grep "M-A" | awk '{print $1}')
			echo tui-progress -bm "$PTS" -c "$CUR" "$CUR/$PT"
			sleep 0.7
		done

I'd expect for each and every single 'line' here the behaviour RudiC reports

Last edited by sea; 05-31-2015 at 08:24 PM..

sea

View Public Profile for sea

Find all posts by sea

05-31-2015

Registered User

12,315, 4,560

Join Date: Jul 2012

Last Activity: 22 November 2019, 4:29 PM EST

Location: San Jose, CA, USA

Posts: 12,315

Thanks Given: 952

Thanked 4,560 Times in 3,818 Posts

What is the output from:

Code:

ls -l vhs.tmp.playstatus
wc vhs.tmp.playstatus
od -bc vhs.tmp.playstatus

Don Cragun

View Public Profile for Don Cragun

Find all posts by Don Cragun

Shell Programming and Scripting

Updating value from new last line of tempfile

8 More Discussions You Might Find Interesting

1. UNIX for Beginners Questions & Answers

Get an output of lines in pattern 1st line then 10th line then 11th line then 20th line and so on.

Discussion started by: Sagar Singh

2. Ubuntu

16.04 not updating

Discussion started by: DabblingMadman

3. SCO

FoxPro 2.6 and updating UW

Discussion started by: AralVorkosigan

4. Shell Programming and Scripting

Need help for updating the folder

Discussion started by: aks_1902

5. AIX

Updating AIX OS

Discussion started by: stayfuzzy

6. Shell Programming and Scripting

updating a single line by script

Discussion started by: ozum

7. Shell Programming and Scripting

Updating a line in a large csv file, with sed/awk?

Discussion started by: trey85stang

8. Shell Programming and Scripting

awk updating one file with another, comparing, updating

Discussion started by: mecano