Who uses 'adb' debugger?

[Clement Lee]

Sorry to ask the following, but I need to know the differences
between (I am a beginner on Unix and C):

  + adb
  + cdb
  + sdb
  + gdb (if you have it;  from GNU)

Can anyone tell me or make a list about their uses and their
differences?

Thanks in advance.

- Clement.

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