git/Documentation/trace2-target-values.txt

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* `0` or `false` - Disables the target.
* `1` or `true` - Writes to `STDERR`.
* `[2-9]` - Writes to the already opened file descriptor.
* `<absolute-pathname>` - Writes to the file in append mode. If the target
already exists and is a directory, the traces will be written to files (one
per process) underneath the given directory.
* `af_unix:[<socket_type>:]<absolute-pathname>` - Write to a
Unix DomainSocket (on platforms that support them).  Socket
type can be either `stream` or `dgram`; if omitted Git will
try both.
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