Bash - creating multiple lists files from one file list

Question

The directory contains x files. I get a list of files. I want to split this list into a larger number of n lists, which would have a limited number of elements.

Examples:

files=$( ls -d /*.csv | sort )
echo $files

/100347_111111.csv
/111301_111111.csv
/111301_222222.csv
/256467_111111.csv
/256467_222222.csv
/256467_333333.csv
/256467_444444.csv
/256467_555555.csv
/256467_666666.csv
/256467_777777.csv

From the resulting list I want to create 3 lists. The lists must not have more than 4 elements. The first list should be composed of the first 4 elements from the files, the other list should contain the following 4 elements, the third list should contain the remaining elements.

n1
/100347_111111.csv
/111301_111111.csv
/111301_222222.csv
/256467_111111.csv

n2
/256467_222222.csv
/256467_333333.csv
/256467_444444.csv
/256467_555555.csv

n3
/256467_666666.csv
/256467_777777.csv

Does someone can help, how to create lists as described above?

I do not know where to start. I think the solution is by using for loop. But I do not really know where to start, I'm an absolute beginner. — kamfulebu
– kamfulebu, Commented Nov 6, 2018 at 10:35
@Amessihel. do you honestly think OP is thinking split or file? — perreal
– perreal, Commented Nov 6, 2018 at 10:41
I do not want to split rows in the file. I want the file name list to be subdivided into sublists. — kamfulebu
– kamfulebu, Commented Nov 6, 2018 at 10:43
there is no need for lists, lists are almost never used in shell. what do you want to do with lists? — perreal
– perreal, Commented Nov 6, 2018 at 10:44
@perreal: maybe not. It's an example (you solved it this way). Another search would be with those keywords: bash for loop number — Amessihel
– Amessihel, Commented Nov 6, 2018 at 10:53

Ravichandra · Accepted Answer · 2018-11-06 11:04:31Z

1

FILES=( `ls -d * | sort`)
echo "${FILES[@]:0:4}"

Loop of 4

count=4
for i in $(seq 0 $(( ${#FILES[@]}/$count - 1 ))) ;
   do  
     echo "######## Set" $i "#######"; 
     echo "${FILES[@]:$(( i * $count )):$count }" ; 
   done

edited Nov 6, 2018 at 11:04

answered Nov 6, 2018 at 10:43

Ravichandra

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1 Comment

Ravichandra Over a year ago

@amessihel modified

Amessihel · Accepted Answer · 2018-11-06 11:32:38Z

1

An example which may be reinventing the wheel:

\ls -1 |
    {
        n=0
        cr=""
        pack=1
        while read -r l
        do
            mod=$(($n % 4))
            if [[ "$mod" == "0" ]]
            then
                echo -e "$cr"n"$pack:"
            fi
            echo $l
            n=$((n + 1))
            pack=$((pack + 1))
            cr="\n";
        done
    }

Here, we use the modulo operator to check if a new pack is about to be displayed (n modulo 4 = 0 if n is a multiple of 4).

I used curly brackets {} to put var initialization and the while loop in the same environment (other wise while won't be able to retrieve n, pack and cr variables).

edited Nov 6, 2018 at 11:32

answered Nov 6, 2018 at 11:26

Amessihel

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Comments

perreal · Accepted Answer · 2018-11-06 10:32:55Z

0

Try split:

ls -d /*.csv | sort | split -l 4 -d

this will create files x01 x02... containing maximum 4 lines.

answered Nov 6, 2018 at 10:32

perreal

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