CODEWITHSUNDEEP
textawkconcatenation
prosmart
prosmart

Reputation: 54

Joining text to the previous line

Currently working on Solaris

I need to search for a specific string in a text file and, if found, join it to the previous line. For example:

if logical condition
then
i = i + 1

Would become

if logical condition then
i = i + 1.

I'm sure I can do this with awk using a hold space of some sort but my awk skills are a little rusty.

Addendum: Apologies, I should have been more specific. The match is triggered by the appearance of the string "then". I have no knowledge of the contents of the previous line - it could be anything. Whatever it is I need to concatenate the "then" to it.

Upvotes: 0

Views: 56

Answers (2)

carl.anderson
carl.anderson

Reputation: 1118

Try this:

awk '
  function dump(trailing_line) {
    for (i = 0; i < length(previous) - 1; i++)
      print previous[i]
    if (trailing_line) { 
      print previous[i] trailing_line 
    } else { 
      print previous[i] 
    }
    i = 0
    delete previous
  }
  /then/ {
    dump(" then")
    next
  }
  {
    previous[i++] = $0
  }
  END {
    dump("")
  }
' your_input_file

If you truly have no knowledge of what comes before the then, you will have to store each line into an array and then dump them out before you emit the then. Since you will also want to do this within the END clause, it's easiest to make this "dumping" action into a function.

Upvotes: 0

Ed Morton
Ed Morton

Reputation: 203502

$ awk '{printf "%s%s", (NR>1?(/then/?FS:RS):""), $0} END{print ""}' file
if logical condition then
i = i + 1

Upvotes: 2

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