From: Junio C Hamano
- If this variable is set git will print trace: messages on + If this variable is set to "1", "2" or "true" (comparison + is case insensitive), git will print trace: messages on stderr telling about alias expansion, built-in command execution and external command execution. + If this variable is set to an integer value greater than 1 + and lower than 10 (strictly) then git will interpret this + value as an open file descriptor and will try to write the + trace messages into this file descriptor. + Alternatively, if this variable is set to an absolute path + (starting with a / character), git will interpret this + as a file path and will try to write the trace messages + into it.