утилита архивирования (an archiving utility)
Возвращаемое значение (Return value)
Tar exit code indicates whether it was able to successfully
perform the requested operation, and if not, what kind of error
occurred.
0 Successful termination.
1 Some files differ. If tar was invoked with the --compare
(--diff, -d) command line option, this means that some
files in the archive differ from their disk counterparts.
If tar was given one of the --create, --append or --update
options, this exit code means that some files were changed
while being archived and so the resulting archive does not
contain the exact copy of the file set.
2 Fatal error. This means that some fatal, unrecoverable
error occurred.
If a subprocess that had been invoked by tar exited with a
nonzero exit code, tar itself exits with that code as well. This
can happen, for example, if a compression option (e.g. -z) was
used and the external compressor program failed. Another example
is rmt failure during backup to a remote device.
