How make bash script using osascript to close app from command line

The pkill command is a compiled binary that directly sends a SIGTERM (-15) signal to a process name that you provide to the script. Can be done from the command-line without the need of a script.

With osascript, you are asking it to interpret, and execute the AppleScript command syntax that tells the operating system to do the same thing as pkill. Far more overhead using osascript.

Your choice of which you use.

osascript is very complicated with shell variables because AppleScript uses double quotes and single quotes.

You have to escape the quotes:

#!/bin/bash
# gracefully close many apps 
for a in "$@"
do
	osascript -e 'quit app "'"$a"'"'
done

See here for more info and how to prevent command line injection: https://stackoverflow.com/questions/23923017/osascript-using-bash-variable-with-a-space/23923167#23923167

No white-space in #!/bin/bash.

#!/bin/bash

: <<'COMMENT'
# alternative way to kiil specified process
echo $1
pkill -x "${1}" -15
COMMENT

osascript -e "tell application \"$1\" to if it is running then quit"
exit 0

The command-line argument must be the identical spelling of the running application name. It must be BBEdit, not bbedit, or any other spelling because pkill is matching on the identical string in the process table.

The same code as you posted with the BBEdit command-line argument works perfectly to kill BBEdit when run here.