Using sed to replace a number greater than a specified number at a specified position

Question

I need to write a script to replace all the numbers greater than an specified number which is in following position.

1499011200 310961583 142550756 313415036 14         


        

Answer 1

This is doable but not simple. (≥ a number ending is 0's is easier than >.)

Let's start with a smaller number.

How could we match numbers greater than 30?

• 2-digit numbers greater than 30 but less than 40,

  \b3[1-9]\b
  

• 2-digit numbers 40 or greater,

  \b[4-9][0-9]\b
  

• numbers with more digits are greater too.

  \b[1-9][0-9]\{2,\}\b
  

Use alternation to match all the cases.

\b\(3[1-9]\|[4-9][0-9]\|[0-9]\{3,\}\)\b

300000000 is similar, but more work. Here I've added spaces for readability, but you'll need to remove them in the sed regex.

\b \( 30000000[1-9]
   \| 3000000[1-9][0-9]
   \| 300000[1-9][0-9]\{2\}
   \| 30000[1-9][0-9]\{3\}
   \| 3000[1-9][0-9]\{4\}
   \| 300[1-9][0-9]\{5\}
   \| 30[1-9][0-9]\{6\}
   \| 3[1-9][0-9]\{7\}
   \| [4-9][0-9]\{8\}
   \| [1-9][0-9]\{9\}
\) \b