I have a flat file (txt/csv) with a single header and many records. I want to use awk/sed/unix tools to strip leading zeros from fields 3 and 5 only on the records (could be one or many leading zeroes). Looked at several solutions, but most don't seem to account for the values being double quoted. Example:


Tried some awk and sed, with printf, regex, etc. Am I missing something already published? ideas? thanks.

Desired output:

  • @Jesse_b - not on the header. added for clarity on that one, could use something like NR >1 if in awk, for example. thanks
    – sirabhorn
    Dec 13, 2019 at 18:33
  • Can any of your quoted fields contain commas or escaped quotes or newlines? If the answer is yes then it becomes a harder problem and if the answer is no then - why are they quoted?
    – Ed Morton
    Dec 13, 2019 at 20:13
  • Ed Morton - they could, but Jesse_b's awk solution targets action only to be taken on fields 3 and 5, which will always be wholly numeric. thanks
    – sirabhorn
    Dec 13, 2019 at 21:42

3 Answers 3


Using awk:

awk -F, '{OFS=","; sub(/"0+/, "\"", $3); sub(/"0+/, "\"", $5)}1'

Shouldn't be an issue unless your header actually has leading zeros but if needed you could do:

awk -F, 'NR > 1{OFS=","; sub(/^"0+/, "\"", $3); sub(/^"0+/, "\"", $5)}1'

This will replace the " and all leading zeros in fields 3 and 5 with just a quote.

  • Great solution and approach on the two fields in question. Thanks for the quick reply!
    – sirabhorn
    Dec 13, 2019 at 18:58

Using Miller, given a CSV file with headers

$ cat file.csv

(silly field names chosen to demonstrate that leading zeros in the header are not affected) then

$ mlr --csv --ofmt '%.0f' --quote-all put '$000003=$000003; $000005=$000005' file.csv

Alternatively, with csvformat (from python csvkit) and numfmt (from GNU Coreutils):

$ csvformat file.csv | numfmt -d, --header --field 3,5 --format '%.0f' | csvformat -U2

Using GNU sed:

$ sed -re '
' file.csv

Assuming that all the fields are quoted.

Mark the third and fifth fields by a newline and remove any leading zeros. In case all are zeros, it will preserve last rather than make the field vanish.

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