Bash – awk + print lines from the first line until match word

You can say:

hasys -display | grep Shutdown | awk '{print $1}' ORS=' '

1. awk normally reads each line of the input and invokes the script on it.  The cases where you would use getline are few and far between.  When your script is run with six lines of input, this is an overview of what happens:

   Read line 1 normally

   Set variables
   Call getline, which reads line 2
   Compare variables

   Read line 3 normally

   Set variables
   Call getline, which reads line 4
   Compare variables

   Read line 5 normally

   Set variables
   Call getline, which reads line 6
   Compare variables

   Obviously this isn’t going to work.

2. Secondly, you made a common mistake in your awk code.  In awk, fields from the input are referenced as $number and variables are referenced as variable_name.  This is different from shell scripts, where command line arguments are referenced as $number and variables are referenced as $variable_name.  Your test

   if ($1 != $path)
   

   should be

   if ($1 != path)
   

3. Your overall approach is flawed.  You can’t identify strings that occur only once in the file by looking at two lines at a time.  I believe that you can do it by looking at three lines at a time (i.e., by keeping the two previous lines in variables), but things like that get complicated and messy.  It’s probably simpler to count occurrences.  Here’s a minimal modification on your script to do that.

   awk '{
     if ($1 != path) {
       if (count == 1) {
         print prev
       }
       count=1
     }
     else count++
     prev=$0; path=$1
   }
   END {
       if (count == 1) {
         print prev
       }
   }'
   

   I deleted type, since you never used it.

   Disclosure: This is essentially the same as the last part of glenn’s answer.