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12-30-2006
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Getting a random file
Hello, I am very new to shell scripting. This problem seems quite easy so it should be quite easy (I hope ^^)
I want to get a random file from a directory. this file will be in one subdirectory, and it will contain spaces. code I have got so far: N=find ./*/*.jpg | wc -l ((N=RANDOM%N)) That gives me a number. Now I want to select the Nth file in this file list generated by find ./*/*.jpg I wanted to use echo ./*/*.jpg except that gave me spaces as a delimiter, which is kind of stupid ^^, since file names contain spaces 
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12-30-2006
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***code removed***
Please see the rules, no classroom/homework posts allowed.
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12-31-2006
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I have reopend this thread becasue the member gave a satisfactory justification for the thread by PM.
Sorry David, seems I was a bit hasty. For future reference if you explain what you are trying to achieve it might avoid this, in particular since you are posting from an educational domain. ksh code: Code:
set +A files ./*/*.jpg # create an array of the files.
N=${#files[@]} # Number of members in the array
((N=RANDOM%N))
randomfile=${files[$N]}
Code:
files=(./*/*.jpg) # create an array of the files.
N=${#files[@]} # Number of members in the array
((N=RANDOM%N))
randomfile=${files[$N]}
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12-31-2006
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My version of ksh (1993-12-28 q) doesn't seem to have a limit either. I did a test to assign values to a array in a loop. I gave up at 700,000 elements.
ksh seems to be twice as fast than bash to assign array values. So, I pushed my little benchmark a little bit further and I assigned 10,000 values to an array and randomly accessed that array 1000 times. Code:
bash real 0m0.623s user 0m0.500s sys 0m0.020s ksh real 0m0.157s user 0m0.160s sys 0m0.000s 
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12-31-2006
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I looked it up in Korn's book: "The subscript for an indexed array can be any arithmetic expression that evaluates between 0 and some implementation-defined value that is at least 4095.
And the O'reilly bash book says: "up to 599147937791" (Of course, you will probably run out of virtual memory before that.) Also ksh is faster than bash for anything that loops because ksh compiles the loop. bash re-interprets the loop each iteration.
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