Sstrhsrtj

I have a variable that contains some numbers then a letter

example: 242M

I need to add a space right before the last character in that variable so that when echo'd it would look like 242 M

I've tried sed but it looks like from what I can find that only works with reading from a file and I haven't been able to get this to work modifying a variable.

Thanks!

A version that should work on any POSIX shell, not just bash:

printf '%sn' "${a%?} ${a#"${a%?}"}"

The extra quotes inside ${a#...} are to protect against special characters from the variable:

$ a='10*M'; printf '%sn' "${a%?} ${a#"${a%?}"}"

10* M

Without them, the second variable expansion would've turned into ${a#10*}, and 10* *M would've been echoed instead.

If the other answer doesn't work (e.g. on macOS), you can also try

a="${a%?} ${a: -1}"

which puts together a without its last character, a space, and the last character of a.

Purely within the shell:

var=${var:0:-1}' '${var: -1:1}

For example:

$ var=jeff

$ var=${var:0:-1}' '${var: -1:1}

$ printf '%sn' "$var"

jef f

Here is a Sed example that works with a variable:

q=242M

sed 's/.$/ &/' <<eof

$q

eof