The sort -R command doesn't sort lines randomly in Linux [closed]

Answer 1

It works on my Ubuntu 8.04 machine. Maybe the problem is the source of randoms. From the manual:

--random-source=FILE

         get random bytes from FILE (default /dev/urandom)

# this should give always the same result:
echo -e '2\n1\n3\n5\n4' | sort -R --random-source=/dev/zero

# this should be random:
echo -e '2\n1\n3\n5\n4' | sort -R --random-source=/dev/urandom

Answer 2

I don't know if bash works this way, but in ksh there's the "whence" command which tells you exactly what will execute if you were to type the argument as a command, whereas "which" just tells you the first instance of the command in $PATH. For instance:

wembley 0 /home/jj33 > which ls
/bin/ls
wembley 0 /home/jj33 > whence ls
'/bin/ls -FC'

I doubt it's your problem, but a next troubleshooting step would be to specify the exact path (or escape a possible alias with a backslash) for "sort" when you execute it:

$ echo -e "2\n1\n3\n5\n4" | /bin/sort -R

After that, I might suspect an environment or locale setting that's making it wonky. Not necessarily important, but the LC_* variables often have unexpected side effects (the first thing I do on a new box is set LC_ALL=C to turn it all off =)).

Answer 3

I know this is an old post, but this solution works very well... just in case someone is looking

dir='/home/path-to-folder'
cd $dir
file=`ls |sort -R |tail --lines=1` 
echo $file

Answer 4

From the GNU coreutils manual:

Sort by hashing the input keys and then sorting the hash values. Choose the hash function at random, ensuring that it is free of collisions so that differing keys have differing hash values. This is like a random permutation of the inputs (see shuf invocation), except that keys with the same value sort together.

If multiple random sort fields are specified, the same random hash function is used for all fields. To use different random hash functions for different fields, you can invoke sort more than once.

GNU sort -R takes the same input and lumps it together; This thread may offer some alternatives: How can I randomize the lines in a file using standard tools on Red Hat Linux?