Data download over the net may have been corrupted or tempered on the way to your computer. Before we can use the data, burn the ISO image to CD or DVD we need to verify the data integrity still intact. The sha1 checksum can be use to check the data integrity of the file that we download. The step by step example below show how to use the sha1sum command or sha1sum utility on Linux Fedora to check the SHA1 checksum value for ISO image file .
1. Check sha1sum utility install on your Linux machine, the command example below locate the sha1sum command.
[root@fedora ~]# whereis sha1sum
sha1sum: /usr/bin/sha1sum /usr/share/man/man1/sha1sum.1.gz
2. Locate the image file that you want to verify the sha1 hash usually image file that end with ISO extension, the example below show the ISO file that we want to check is on the root directory.
[root@fedora ~]# ls
anaconda-ks.cfg Documents install.log Pictures Videos
dban-1.0.7_i386.iso Download install.log.syslog Public
Desktop fedora9 Music Templates
3. To check the sha1sum value of the file... execute the sha1sum and the the filename of the ISO image that you want to check the sha1 value as shown on example below.
[root@fedora ~]# sha1sum dban-1.0.7_i386.iso
5. The sha1sum result below show the sha1 value for the dban-1.0.7_i386.iso.... compare the sha1 value that you get from the sha1 value on the downloaded server.
|Sha1sum value||File Name|
Get help using the sha1sum command:
[root@fedora ~]# sha1sum --help
Usage: sha1sum [OPTION] [FILE]...
Print or check SHA1 (160-bit) checksums.
With no FILE, or when FILE is -, read standard input.
-b, --binary read in binary mode
-c, --check read SHA1 sums from the FILEs and check them
-t, --text read in text mode (default)
The following two options are useful only when verifying checksums:
--status don't output anything, status code shows success
-w, --warn warn about improperly formatted checksum lines
--help display this help and exit
--version output version information and exit
The sums are computed as described in FIPS-180-1. When checking, the input
should be a former output of this program. The default mode is to print
a line with checksum, a character indicating type (`*' for binary, ` ' for
text), and name for each FILE.
Report bugs to <email@example.com>.