Given a simplified CSV (max one line per row) with many data fields (>50), how can I count the maximum character length for each data field and then export all the counts to a txt file? BTW, I want to ignore the first line of the file which contains the column headings.

For example, given the input


The end result could be something like the following, where the first column indicates the data fields in the original file and the second column indicates the maximum length of the field:

1 | 10
2 | 11
3 | 12
4 | 13

i.e., the length of the longest value in column 1 is 10 (abcdefghij), the length of the longest value in column 2 is 11 (abcdefghijk), etc.

I have researched on the site a little bit and found couple ways that can count maximum length in a fairly straightforward manner when a certain data field is specified. For example, use cut and wc commands to count maximum length of the second field in the file:

cut -d, -f2 test.csv | wc -L  

But how can I take the command and loop it over to all the data fields and then output?

  • Can you give some sample input?
    – cuonglm
    Sep 15, 2014 at 16:45
  • Sure. You can download the sample file via this link: drive.google.com/file/d/0B3-WolEQUW6yM3NZUGhHaVFmdFk/… the sample file has 10 columns. thanks
    – QY Luo
    Sep 15, 2014 at 17:01
  • I had a problem with your link. Can you please just post a small example in your question? Sep 15, 2014 at 17:24
  • sorry guys, just fixed the link. please try again. thx!
    – QY Luo
    Sep 15, 2014 at 17:26
  • guys, since HalosGhost edited the question with a perfect input example, I am going to take the link down. thank.
    – QY Luo
    Sep 15, 2014 at 20:42

2 Answers 2


If I understand your question correctly, this will do what you want:

awk -F, 'NR!=1 { if (max_NF < NF) max_NF = NF;
                 for (i=1; i<=NF; i++) if (max[i] < length($i)) max[i] = length($i) }
         END   { for (i=1; i<=max_NF; i++) printf "%-2d | %d\n", i, max[i] }'
  • this works! G-man, you are the man. thx
    – QY Luo
    Sep 15, 2014 at 18:04
  • @StéphaneChazelas: (1) “Note that you've got no guarantee of order with for (i in max) …” Good point. (2) “That would also cover for columns with only empty fields.” Huh? My current solution handles columns with only empty fields. Sep 15, 2014 at 20:22
  • @StéphaneChazelas: I applied your suggestion, however there is nothing returned. Here is the code, am I making any mistake? awk -F, 'NR!=1 { for (i=1; i<=NF; i++) if (max[i] < length($i)) max[i] = length($i) } END { for (i=1; i<=max_NF; i++) printf "%-2d| %d\n", i, max[i] }' 2014-07-08.csv
    – QY Luo
    Sep 15, 2014 at 21:09
  • @QYLuo: You need to add code to set max_NF; see my edit. Sep 15, 2014 at 21:16
  • regarding empty columns, yes, sorry, I had overlooked the fact that accessing max[i] instantiates the array element. Note that length(max) will give you max_NF in GNU awk (but GNU awk only). Sep 15, 2014 at 21:43

I don't see your link for the sample file but you can do this by using awk command. if can specify what ever delimiter you may have and exactly what field you need to count.

    awk '{ FS = "," } ; { if(NR!=1) gsub(/"/, "", $2) ; print NR "|" length($2) } ' test.csv

You can redirect this output to any file you want.

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