Shell Programming and Scripting

What is the best way to specifically name an output file in a bash script? My current script has the following output code.

Code:

awk 'BEGIN {print "CASE          GID   vd      d-theta  GID   vd     d-theta"} {print $0}' > "$TOL"_try.txt

The variable $TOL is an input to the script. I would like to prefix the name of the output file with only the first two characters of the input variable $TOL. e.g....

If $TOL = 1X_in then I would like my output file to be 1X_try.txt

Thanks

Code:

n=${TOL:0:2}

in bash gives the first two characters of the variable TOL

Thanks Jim. Worked great.

What does the 0 mean in the expression?

The 0 is the offset, denoting the beginning of the substring slice. From https://www.unix.com/man-page/Linux/1/bash/
Note, the text I abbreviated with "...." contains some important details, so read it for yourself ;)

Just in case anyone saw the above and wondered how that can be done in a posix-compliant manner:

Code:

printf '%.2s_try.txt' "$TOL"

Regards,
Alister

Thanks for the info and the link alister.