Question

if [`read -n1 -s`='y']

is causing

./bzfsctl.sh: line 17: [=y]: command not found

Even

if [1=1]

produces:

./bzfsctl.sh: line 17: [1=1]: command not found

EDIT After properly adding in the spaces get

./bzfsctl.sh: line 16: [: -eq: unary operator expected

with

if [ `read -n1 -s` = 'y' ]
then
echo 'killing process ...'
else
echo 'Aborted'
fi

Answer 1

You need to be careful with the spaces in your commands.

if [ 1 = 1 ]; then echo Ok ; fi
    ^ ^ ^ ^

All four of these spaces are necessary.

If you want to read a single char and test it:

read -n1 input
if [ $input = "y" ] ; then echo Got a Yes ; fi

When you write if something ; then ... the shell executes something and then acts depending on the return code of that command.

[ isn’t “syntax”, it’s a program (or shell built-in), that is also called test.

So:

if [ $a = $b ] ; then ...

actually runs the executable (or built-in) [ with the arguments $a, =, $b and ].

If you don’t put the brackets, you need the thing between the if and ; to be a regular executable command that returns 0 on success.