sigh, ++ to Anonymous
if you have cool text tools (some sort/uniq/cut are really lame) it's even easier to accomplish
$ cat -n config.log | head
1 This file contains any messages produced by compilers while
2 running configure, to aid debugging if configure makes a mista
+ke.
3
4 It was created by configure, which was
5 generated by GNU Autoconf 2.57. Invocation command line was
6
7 $ ./configure
8
9 ## --------- ##
10 ## Platform. ##
# lines 3,6,8 are the duplicates in this little test.
# fields are tab seperated.
$ cat -n config.log | head | # number the lines
sort -k 2 | # sort on second field
uniq -f 1 | # uniq skipping first field
sort -k 1,1n | # numeric sort on first field
cut -f2 # extract second field
This file contains any messages produced by compilers while
running configure, to aid debugging if configure makes a mistake.
It was created by configure, which was
generated by GNU Autoconf 2.57. Invocation command line was
$ ./configure
## --------- ##
## Platform. ##