Acme/plan9: Runs a command in a window, as with button 2

Aexe

#!/bin/rc
# Runs a command in an acme window, as with button 2
# Tries to restore original selection.

rfork e

if(! ~ $#* 1 2)
	exit 'usage: exe PARAM [WINID]'
cmd=$1
id=$2

if(~ $#id 0)
	id=$winid
w=/mnt/acme/$id
if(! test -d $w)
	exit 'invalid window id:'^$id

if(echo $cmd | grep -s '^[ 	]*(Put|Putall)[ 	]*$')
	exit 'invalid command: '^$cmd
# using a temp file to avoid issues with `{} swallowing tabs
cmdfile=/tmp/Aexe.$pid
echo -n $cmd >$cmdfile
cmdlen=`{wc -r <$cmdfile}

# save selection
<$w/addr {
	echo 'addr=dot' >$w/ctl
	preaddr=`{cat | awk '{print "#" $1 ",#" $2}'}
}

# detect 'Edit ,' or whole text selection
commarx='^[ 	]*Edit[ 	]+,'
if(echo $cmd | grep -s $commarx){
	sed 's/'^$commarx^'/Edit /' <$cmdfile >$cmdfile.2
	mv $cmdfile.2 $cmdfile
	bodylen=`{cat $w/body | wc -r}
	addr='#0,#'^$bodylen
}
if not
	addr=$preaddr

# construct event
beg=`{cat $w/body | wc -r}
cat $cmdfile > $w/body
end=`{echo $beg + $cmdlen | hoc}
event=MX^$beg^' '^$end

# run command on hacked selection
echo -n $addr >$w/addr
echo 'dot=addr' >$w/ctl
echo $event >$w/event

# save post-command selection
<$w/addr {
	echo 'addr=dot' >$w/ctl
	postaddr=`{cat | awk '{print "#" $1 ",#" $2}'}
}

# delete command text
>$w/addr {
	echo -n '$-#'^$cmdlen^',$'
	echo 'dot=addr' >$w/ctl
	echo -n >$w/wrsel
	# restore post-command selection
	echo -n $postaddr
	echo 'dot=addr' >$w/ctl
}
rm $cmdfile