Shell Programming and Scripting

Even with ERE, you need to run it twice, perhaps conditionally if the first hits, as you used both start and end field '|'. Otherwise, you miss the following adjacent fields on a line like: "123.|456."

You can add pipes to both ends for the substitute and then remove them:

Code:

sed '
  s/.*/|&|/
  s/\(|[0-9]\{1,99\}\)\.|/\1|/g
  t again
  b end
  :again
  s/\(|[0-9]\{1,99\}\)\.|/\1|/g
  :end
  s/^|//
  s/|$//
 ' in_file

I could have removed both added pipes with one substitute "s/^|\(.*\)|$/\1/" but these back references are a bit slower, in my experience, so I avoid them where possible.

Two passes can be avoided if a less careful pattern is sought, like "s/\([0-9]\).|/\1/", as it encompasses only one pipe. It mangles any non-numeric field with a trailing numer and dot, like "123|The field count of this line is 3.|xyz".