To become a user that has /bin/false as shell:
# su - user -s /bin/<some shell>
$ sort FILE | uniq -D
(Must sort since uniq will only look at consecutive lines)
Can also limit the number of characters to compare, e.g. 20 characters:
$ sort FILE | uniq -D -w 20
source: http://www.linuxquestions.org/questions/linux-software-2/finding-duplicate-lines-in-a-file-617441/
The method above can be used with a list of hashes to locate identical files:
$ md5sum * > MD5SUMS $ sort MD5SUMS | uniq -D -w 32
Source: Dd - Destroyer of disks
(A simple dd will work but might carry some extra garbage)
Discover sector size (2048 for standard ISOs) and ISO size:
$ isoinfo -d -i /dev/cdrom ... # e.g.: Logical Block Size: 2048 # <- sector size ... Volume Space Size: 123456 # ISO size $ dd if=/dev/cdrom bs=2048 count=123456 conv=noerror of=image.iso
conv=notrunc Appends to output
conv=noerror Continues after read errors
(can be combined with conv=notrunc,noerror)
$ vcdxrip -C # Part of vcdimager