Why is cat running as a daemon on Ubuntu 12.04?

cat is running as part of the Unity Dash Text-Search service (zeitgeist-fts)

cat is not a daemon; conCATenate is a utility which joins one or more input files into a single output file.

  • /bin/cat runs on Ubuntu 12.04 as a part of the Zeitgeist service, which logs events, history, etc. and also enables the search-as-you-type in the dash feature.

  • Specifically, it is started by zeitgeist-fts (Zeitgeist Full-Text-Search), which is the Zeitgeist component providing the search feature.

  • Proof: notice the PID of cat (3082) in ps andpstree output:

    $ ps aux | grep /bin/cat
    izx       3082  0.0  0.0  11372   568 ?        S    Jun08   0:00 /bin/cat
    
    and
    $ pstree -p | grep zeit
    ├─zeitgeist-daemo(3051)───{zeitgeist-daemo}(3061)
        ├─zeitgeist-datah(3076)───{zeitgeist-datah}(3081)
        └─zeitgeist-fts(3075)─┬─cat(3082)
                              └─{zeitgeist-fts}(3080)
    
  • Zeitgeist/Unity did not exist in 10.04, so no cat either! As for why it's needed, cat is universally used for text processing, and the function of its parent zeitgeist-fts is...text processing :)