I know this should be simple, but sorry I am fairly new to UNIX and can't find the syntax to make this work.

I have following two commands in a script:

x=`expr $(head -1 filename.ext | cut -c16 | grep [A-Z] | wc -l) + 16`
del=`head -1 filename.ext | cut -c$x`

This works fine as I expect it to.  But I want to combine it into one command.  Essentially I just want the entire expression that I am assigning to x in the first command to be evaluated at the end of the second command as my argument to the -c attribute of the cut command.  But I've tried every way I can to get it to evaluate properly and can't get it.  

Thanks for any help.
 

With backquotes that is kind of hard, with $(cmd) construct it is easier and more readable:

del=$(head -1 filename.ext | cut -c$(expr $(head -1 filename.ext | cut -c16 | grep [A-Z] | wc -l) + 16))

But I guess there are easier ways to accomplish the same result.

If an uppercase letter is at position 16 in 1st line, use char at 17th position. I'd probably use awk for that.

HTH,

p5wizard

x will return either 16 or 17

17 if the 16'th character of the first line in file filename.ext is uppercase (range of A-Z), otherwise it will return 16


head -1 filename.ext |cut -c16 |grep [A-Z] && {
  # 16th character is in range A-Z
  head -1 filename.ext |cut -c17
} || {
  # 16th character is not in range of A-Z
  head -1 filename.ext |cut -c16
}

I used the curly brackets to make it more readable as well as show that you can use several lines of command

Compressed into one line:
head -1 filename.ext |cut -c16 |grep -q [A-Z] && head -1 filename.ext |cut -c17 || head -1 filename.ext |cut -c16
 

I forgot to use -q with grep, in the curly brackets example :)

Explanation:
'grep -q'
  - is a quiet grep and will only tell you if it found the expression or not.

Based on the return code from grep I either cut the 17th or the 16th character out from the output of 'head -1 filename.ext'

---- so an appropriate answer to your question could be:
del=`head -1 filename.ext |cut -c16 |grep -q [A-Z] && head -1 filename.ext |cut -c17 || head -1 filename.ext |cut -c16`

/2r