Why is cat running as a daemon on Ubuntu 12.04?

Question

/bin/cat appears to be running as a persistent daemon on my 12.04 system.

$ ps aux | grep cat

detlef 2278 0.0 0.0 8680 352 ? S 06:13 0:00 /bin/cat

Why does Ubuntu 12.04 need cat running as a daemon? It didn't on my 10.04.4 system.

Answer 1

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 :)