[lemma=back] [word=a] [□]
[lemma=back] [word=a] [□=□]
[lemma=back] [word=a] [□ | □]
You invoke ifnames with a list of file names ( you can also pipe the files to ifnames through stdin ) , and it spits back a sorted list of all the #if , #ifdef , #elif , and #ifndef statements it finds .