One line while-loop in bash creating list of variables

Question

I am attempting to write a 1 line while loop that creates a string of file names like list="temp0.txt temp1.txt temp2.txt ... " etc.. I want it to be a random number of files between 0 and 50, and this is what I have thus far.

argumentCount=$RANDOM
let "argumentCount %= 50"
i=0
list=""
while [ $i -lt $argumentCount ]; do; touch temp[$i].txt; $list="$list temp[$i].txt; ((i=i+1)); done
countLines $list > output.txt

I am trying to declare a random number between 0 and 50, and then using a while loop I want to create the same number of files as this random number. I want to then create a string that has all of the file names listed one after the other. This string will then be passed to countLines, which is a program that accepts any number of filenames as parameters.

I have this set of commands stored in a different file, and I am using eval on each line in this file, but it is giving me a syntax error. Is there something I can do to make it work? Thanks

printf -v varname "temp%03d.txt" $(($RANDOM % 50)) Then $varname will contain temp000.txt - temp049.txt randomly. (you can control the number of leading '0's with the printf format specifier. (add $(($RANDOM % 50 + 1)) for 001 - 050 numbering). — David C. Rankin
– David C. Rankin, Commented Feb 5, 2017 at 4:29
I am looking to make multiple files, but a random number of files. — Sean Morgan
– Sean Morgan, Commented Feb 5, 2017 at 4:34
@SeanMorgan: Can you provide a minimal verifiable input and expected output. Your current code/requirement is not clear. State exactly your input and output required — Inian
– Inian, Commented Feb 5, 2017 at 4:36
You need some exit condition for your loop. You just can't continue to randomly create files forever. You can use a counter (e.g. declare -i n=0) and in your file-create loop to ((n++)) and test "$n" -gt '40' && break if you like. (or whatever number you like). You also need to check for an existing file of the same name/number (e.g. test -f "$varname" && continue to generate a non-conflicting filename) — David C. Rankin
– David C. Rankin, Commented Feb 5, 2017 at 4:37
In your existing while loop line, try dropping the ';' after do and '$' in '$list=' — viral_mutant
– viral_mutant, Commented Feb 5, 2017 at 4:41

score 1 · Accepted Answer · 2017-02-05 06:05:15Z

1

This will print a line with file names:

eval echo temp{1..$((RANDOM%50))}.txt

And this will touch the list of files:

eval touch temp{1..$((RANDOM%50))}.txt

And this script will do all the things yours do:

#!/bin/bash

list=$( eval echo '"temp["{1..'$((RANDOM%50))'}"].txt"' )

touch $list

countLines "$list" > output.txt

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