Count line lengths in file using command line tools

Problem

If I have a long file with lots of lines of varying lengths, how can I count the occurrences of each line length?

Example:

file.txt

this
is
a
sample
file
with
several
lines
of
varying
length

Running count_line_lengths file.txt would give:

Length Occurences
1      1
2      2
4      3
5      1
6      2
7      2

Ideas?

This

• counts the line lengths using awk, then
• sorts the (numeric) line lengths using sort -n and finally
• counts the unique line length values uniq -c.

$ awk '{print length}' input.txt | sort -n | uniq -c
      1 1
      2 2
      3 4
      1 5
      2 6
      2 7

In the output, the first column is the number of lines with the given length, and the second column is the line length.