Help me understand a thing or two

Ramiferous

I am always asking more or less technical questions so I thought maybe I'll start my own thread where I can post about things I am trying to understand in the hope that some of you can share your knowledge, and perhaps some tutorage with me.

What am I trying to do:

I want my barscript.sh (that I am using with sdorfehs wm) to indicate when my speakers are muted.

What I've tried:

xev output of my ThinkPad X230's mute button is as expected: XF86AudioMute
However, because toggling the mute botton on/off outputs the exact same information, I figure I need to write a short script?

So, I discovered the commands to mute and unmute are:
mixerctl -w outputs.master3.mute=on
mixerctl -w outputs.master3.mute=off
So with absolutely little to no scripting knowledge, I whipped up this simple script:

mute.sh:

#!/bin/sh

MUTE=$(mixerctl outputs.master3.mute | sed 's/^outputs.master3.mute=//')

if [ "${MUTE}" = "off" ]; then
    RUN='mixerctl -w outputs.master3.mute=on'
else
    RUN='mixerctl -w outputs.master3.mute=off'
fi

exec "$RUN"

This is clearly where I'm going wrong because the script don't work!

Running mute.sh gives this error:
exec: mixerctl -w outputs.master3.mute=on: not found

Nevertheless, I added this keybinding to my wm config:
definekey top XF86AudioMute exec $HOME/.scripts/mute.sh

Running the command mixerctl -w outputs.master3.mute=on in a terminal works, and after adding the relevant bits to my barscript.sh I do get the desired output in my bar: [68%MUTE]. It's just the mute.sh script that isn't working and my lack of basic shell scripting is clearly the reason why.

For reference, my barscript.sh:

#!/bin/sh

while true; do

# Packages
PKGS="$(pkg_info | wc -l | sed -e 's/^[ \t]*//')"

# Volume
LEV="$(mixerctl outputs.master | sed -e 's|.*,||g')"
VOL="$name$(expr \( $LEV \* 100 \) / 254)"
MUTESTATE=$(mixerctl outputs.master3.mute | sed 's/^outputs.master3.mute=//')
if [ "${MUTESTATE}" = "on" ]; then
    MUTE=' MUTE'
else
    MUTE=''
fi

# Battery
BAT_PERC="$(envstat -s acpibat0:charge | tail -1 | sed -e 's,.*(\([ ]*[0-9]*\)\..*,\1,g')%"
BAT_STATE="$(envstat -d acpibat0 | awk 'FNR == 10 {print $2}')"
if [ "${BAT_STATE}" = "TRUE" ]; then
    STATE='+'
else
    STATE='-'
fi

# Date
D="$(date '+%a %d %b %I:%M')"

# Weather
WTTR="$(cat $HOME/.scripts/weather.txt)"

# Print
echo "$D ~ $WTTR [$PKGS#][$VOL%$MUTE][$STATE$BAT_PERC]" > ~/.config/sdorfehs/bar

sleep 1
done
exit 0

The output of barscript.sh is sent to ~/.config/sdorfehs/bar which is then read by the wm through some sort of unix wizardry which I don't understand.

I would love to know what I'm doing wrong or how this could be done better.

rvp

Ramiferous Running mute.sh gives this error:
exec: mixerctl -w outputs.master3.mute=on: not found

Remove the exec and quotes around $RUN; or, use this somewhat shorter version:

#!/bin/sh
#
# Toggle audio mute state.
exec mixerctl -w outputs.master3.mute++

And, for barscript.sh, you don't need to use expr; just calculate it directly using $((...)).

Ramiferous

rvp Remove the exec and quotes around $RUN; or, use this somewhat shorter version:
#!/bin/sh
#
#Toggle audio mute state.
exec mixerctl -w outputs.master3.mute++

In that case I don't need a mute script at all, I've just remapped the mute button with:
definekey top XF86AudioMute exec mixerctl -w outputs.master3.mute++

This works 🙂
This also leads me to wonder, is ++ a universal argument for toggle on/off ?

rvp And, for barscript.sh, you don't need to use expr; just calculate it directly using $((...)).

I guess your talking about the VOL line:
VOL="$name$(expr $ $LEV \* 100 $ / 254)"

This was something that I stole from @pin when I was using his unibar config. I'm not exactly sure how you mean it should be calculated directly.

rvp

Ramiferous n that case I don't need a mute script at all, I've just remapped the mute button with:
definekey top XF86AudioMute exec mixerctl -w outputs.master3.mute++

Remove exec--it's only useful inside shell scripts.

Ramiferous This also leads me to wonder, is ++ a universal argument for toggle on/off ?

You can also use:--, +=1, -=1 (All of this is documented in the man page.)

Ramiferous I'm not exactly sure how you mean it should be calculated directly.

LIke this--no expr needed in a POSIX shell:

#!/bin/sh

n=1
while [ $n -le 12 ]
do	for i in $(seq 1 10)
	do	printf "$n x $i = $((n * i))\t"
		printf "$((n+1)) x $i = $(((n+1) * i))\t"
		printf "$((n+2)) x $i = $(((n+2) * i))\t"
		printf "$((n+3)) x $i = $(((n+3) * i))\n"
	done
	printf "\n"
	n=$((n + 4))
done

Ramiferous

rvp Remove exec--it's only useful inside shell scripts.

Inside the sdorfehs config file exec is necessary. I don't know why, but this is how you set executable key bindings.

rvp LIke this--no expr needed in a POSIX shell:

This would explain why when I kill the X server I see a whole bunch of this:

...
expr: syntax error
expr: syntax error
expr: syntax error
expr: syntax error
expr: syntax error
...

EDIT: It took me a few shots to figure it out but I got there in the end with

VOL="$((( $LEV ) * 100 / 254))"
😄

EDIT2: Still getting expr: syntax error after killing X server though

Ramiferous Still getting expr: syntax error after killing X server though

This is most probably unrelated.
I did try to look if I could find anything by taking a pick at your config files but, I gave-up straight away when I saw your .shrc 😨

Do you use a dictionary to look-up all that stuff? 🤣

136 lines .shrc 😱

rvp

Ramiferous Inside the sdorfehs config file exec is necessary.

Ah--I see...

Ramiferous This would explain why when I kill the X server I see a whole bunch of this:

Some other error, this, I think.

Ramiferous EDIT: It took me a few shots to figure it out but I got there in the end with
VOL="$((( $LEV ) * 100 / 254))"

I would group the operands this way to make things clearer: VOL=$(( (LEV * 100) / 254 ))

There are other shortcuts that you can take to reduce the no. of commands run each second.

Use the -n flag to mixerctl to omit the variable name instead of removing it using sed:
Ie. instead of this:

$ mixerctl outputs.master3.mute | sed 's/^outputs.master3.mute=//'
off
$

do this:

$ mixerctl -n outputs.master3.mute
off
$

Use the shell's prefix and suffix removal feature instead of sed/awk:
This:

$ envstat -d acpibat0 | awk 'FNR == 10 {print $2}'
FALSE
$

can be written without awk:

$ O=$(envstat -d acpibat0)	# stash output
$ BAT_CH=${O##*charging:}	# remove BOL to `charging:' (incl.)
$ BAT_CH=${BAT_CH%charge*}	# remove `charge...' (incl.) to end
$ echo $BAT_CH			# do _not_ quote this.
FALSE
$

In similar vein, you can make multiple passes over the same data and skip running separate commands each time to the extract pieces you want.

As a demo, I've re-written your barscript.sh like this:

#!/bin/sh

set -eu
while :
do
	# Packages
	PKGS=$(pkg_info | wc -l)
	PKGS=${PKGS##* }		# strip leading spaces

	# Volume
	VOL=$(mixerctl -n outputs.master)
	VOL=${VOL%,*}			# strip other channel
	VOL=$(( (VOL * 100) / 254 ))
	MUTE=$(mixerctl -n outputs.master3.mute)
	if [ $MUTE = on ]
	then	MUTE=" MUTE"
	else	MUTE=""
	fi

	# Battery
	O=$(envstat -s 'acpibat0:charge,acpibat0:charging,acpibat0:discharge rate')
	BAT_PERC=${O#*(}		# strip from beginning to '('
	BAT_PERC=${BAT_PERC%%.*}	# strip from first '.' to end
	BAT_DIS=${O#*discharge rate:}	# strip ^ -> 'discharge rate:' (incl.)
	BAT_DIS=${BAT_DIS%charg*}	# snag discharge rate, or "N/A"
	BAT_DIS=${BAT_DIS%W*}		#  " (contd.)
	BAT_STATE=${O#*charging:}	# snag charge state

	if [ $BAT_DIS != N/A ]		# note: do not quote any of these
	then	STATE="-"		# discharging
	elif [ $BAT_STATE = TRUE ]
	then	STATE="+"		# charging
	else	STATE="="		# topped-up
	fi

	# Date
	D=$(date '+%a %d %b %I:%M')

	# Weather
	WTTR=$(cat $HOME/.scripts/weather.txt)

	# Print
	echo "$D ~ $WTTR [$PKGS#][$VOL%$MUTE][$STATE$BAT_PERC%]" > ~/.config/sdorfehs/bar

	sleep 1
done

Further "optimizations" (eg. removing the extra mixerctl to get the mute state) are up to you.

Ramiferous

pin Do you use a dictionary to look-up all that stuff? 🤣

136 lines .shrc 😱

haha yeah, mostly alias's. Is it better to use a separate file for Alias's? Believe it or not I remember most of them.
In a way, it's kind of a personal knowledge base for commands I would otherwise forget.

rvp
Wow, that's awesome thanks! I'll try it out 😃

EDIT: Works like a charm 😉

Now lets say I wanted to add uptime to the bar as well. In previous bar scripts I had used this line:

UP="$(uptime | awk -F, '{sub(".*up ",x,$1);print $1}' | sed -e 's/^[ \t]*//')"

Is there a neater/simpler way to get the same output without sed of awk ?

pin This is most probably unrelated.
I did try to look if I could find anything by taking a pick at your config files but, I gave-up straight away when I saw your .shrc

Any way of knowing which file is causing the error?

rvp

Ramiferous Is there a neater/simpler way to get the same output without sed of awk ?

UP=$(uptime)
UP=${UP#*up}
UP=${UP%%,*}
echo $UP

yeti

Ramiferous Is there a neater/simpler way to get the same output without sed of awk ?

$ UP=$(set - $(uptime) ; echo $3 days)
$ echo $UP
39 days

Ramiferous

rvp 👍️ This does the trick. The only thing which is strange is, I like to encase each output in [square brackets] however when I do this I get a trailing space after the first bracket like so: [ 14 minutes]. This triggers my OCD slightly 😟 I've just added the bracked to the echo line at the end like this:

UP=$(uptime)
UP=${UP#*up}
UP=${UP%%,*}
echo [$UP]

yeti Nice! However, I shutdown my laptop when I'm done using it so no need for "days" 😆

yeti

Ramiferous yeti Nice! However, I shutdown my laptop when I'm done using it so no need for "days" 😆

Without "days" it even is shorter... ;-)
I only kept it because your original awk/sed dance had it.