CODEWITHSUNDEEP
fileunixrandom
gameboyprinter
gameboyprinter

Reputation: 55

get many lines randomly form a file without shuffling them

I need to, using a UNIX command line script, get 11 random lines from a file that are grouped together. For instance

Random source file:

1
2
3
4
5
6
7
8
9
10
11
############
12
13
14
15
16
17
18
19
20
21
22

Running ./myscript should give me:

1
2
3
4
5
6
7
8
9
10
11

or

12
13
14
15
16
17
18
19
20
21
22

Upvotes: 2

Views: 152

Answers (2)

codaddict
codaddict

Reputation: 455460

You can try:

n=$((`wc -l "${file}" | cut -d' ' -f1` / 11))
m=$(($RANDOM % $n))
tail -n +$(($m * 11)) "${file}" | head -n 11

Upvotes: 0

sehe
sehe

Reputation: 394034

tail -n +$(($RANDOM % 
     ($(wc -l "$filename" | cut -d' ' -f1) - 11))) "$filename" |
     head -n 11

Tested

With

export filename=/etc/dictionaries-common/words
set -o xtrace

first time

~$ tail -n +$(($RANDOM % ($(wc -l "$filename" | cut -d' ' -f1) - 11))) "$filename" | head -n 11
+ head -n 11
++ wc -l /etc/dictionaries-common/words
++ cut '-d ' -f1
+ tail -n +11614 /etc/dictionaries-common/words
Moriarty's
Morin
Morin's
Morison
Morison's
Morita
Morita's
Morley
Morley's
Mormon
Mormon's

second time

~$ tail -n +$(($RANDOM % ($(wc -l "$filename" | cut -d' ' -f1) - 11))) "$filename" | head -n 11
+ head -n 11
++ wc -l /etc/dictionaries-common/words
++ cut '-d ' -f1
+ tail -n +1661 /etc/dictionaries-common/words
Beatrice
Beatrice's
Beatrix
Beatrix's
Beatriz
Beatriz's
Beau
Beau's
Beaufort
Beaufort's
Beaujolais

Upvotes: 2

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