AWK is good for this:

awk '{while ($1-- > 0) print $2}' test.txt

This interprets each line of test.txt as a record of fields separated by spaces. It counts down (--) from the value of the first field ($1) until that value is zero, printing the value of the second field ($2) on its own line each time.

One of the advantages of this method is that it automatically tolerates extra whitespace before, in between, or after the numbers.

Specifically:

• $1 and $2 are the first and second fields.


• The while-loop evaluates the expression $1-- > 0. If it's true, then print $2 runs, then starts over again.


• The subexpression $1-- diminishes the value of the first field by one. (This happens in memory; the actual file text.txt is never modified.) But it returns the value $1 had just before it was decreased. See Gawk: Effective AWK Programming, section 6.2.4 Increment and Decrement Operators, for a more thorough explanation.

If you prefer, you can instead use a for-loop:

awk '{for (; $1 > 0; --$1) print $2}' test.txt

Or with a dedicated loop counter variable:

awk '{for (i = $1; i > 0; --i) print $2}' test.txt

Or if you find it more intuitive to count up instead of down, you can do that:

awk '{for (i = 0; i < $1; ++i) print $2}' test.txt