tar
itself does not write down a checksum for later comparsion. If you gzip
the tar
archive you can have that functionality.
tar
uses compress
. If you use the -Z
flag while creating the archive tar
will use the compress
program when reading or writing the archive. From the gzip
manpage:
The standard compress format was not designed to allow consistency
checks.
But, you can use the -z
parameter. Then tar
reads and writes the archive through gzip
. And gzip
writes a crc checksum. To display that checksum use that command:
$ gzip -lv archive.tar.gz
method crc date time compressed uncompressed ratio uncompressed_name
defla 3f641c33 Sep 25 14:01 24270 122880 80.3% archive.tar
From the gzip
manpage:
When using the first two formats (gzip or zip is meant), gunzip checks
a 32 bit CRC.