I need for the 5th column in a delimited text file to be reduced to just the first 5 characters. All other columns must remain unedited.


file1.txt    column1      column2      column3     column4      column5
123456789    123456789    123456789   123456789    123456789

I would like the output to look like:

output.txt    column1      column2      column3     column4      column5
123456789    123456789    123456789   123456789    12345

Note: I happen to use commas as the delimiter.

  • 1
    This doesn't look like a CSV file as commas/semicolons are missing. Are those tabs between the values?. Can this table have quoted values with newlines like a CSV file? In general you cannot use text-processing tools on CSV, you need a real parser except for not so realistic simple cases. Never more than 5 columns? If not what about alignment? – Anthon Nov 11 '14 at 14:38
  • I can change the delimiter to whatever is needed. I just typically use commas. The example I provided is obviously just a visual representation of what I am looking for, not an actual CSV. If it would make the question easier, I could easily update the table, but I guess I assumed someone would have a quick command off the top of their head. – cmart2112 Nov 11 '14 at 14:41
  • For real CSV files, you need to use Perl or Python with an appropriate library, otherwise you'll break the file. If this is a simple subset of CSV (no quoted values, no newlines in values, etc.) you should clearly indicate that, then simpler solutions with awk/sed etc can be given. – Anthon Nov 11 '14 at 14:46

If file.csv looks like this:


Then, you can do:

$ awk -F, '{print $1","$2","$3","$4","substr($5,1,5) }' file.csv
  • 1
    You can do it more portable awk -F, -v OFS="," '{$5=substr($5,1,5)}1' – Costas Nov 11 '14 at 15:11
  • 1
    To pass 1 line with headers just modify awk -F, -v OFS="," 'NR>1{$5=substr($5,1,5)}1' – Costas Nov 11 '14 at 16:42

If all the values are simple (no quotes and newlines in a value) and if they are comma separated, like:


and if there are always 5 such values on a line, you can use sed:

sed '2,$s/\(.*\),\(.*\),\(.*\),\(.*\),\(.....\)\(.*\)/\1,\2,\3,\4,\5/' input

The 2,$ assumes you have a header that is comma separated as well (and that its fifth column should not be truncated), if that is not the case leave it out.

  • If all first columns have fields more then 5 symbol length you can make script more portable sed 's/\([^,]\{5\}\)[^,]*/\1/5' < input – Costas Nov 11 '14 at 14:59
  • To edit above variant to work with any length fields sed '2,$ s/\([^,]\{,5\}\)[^,]*/\1/5' < input – Costas Nov 11 '14 at 15:07

Or awk:

For white-space delimited:

awk 'NR==1 { print; next} {print $1, $2, $3, $4, substr($5,1,5)}'

For comma delimited:

awk 'BEGIN {FS=","} NR==1 { print; next} {print $1, $2, $3, $4, substr($5,1,5)}'

For slightly better CSV splitting and assuming GNU awk:

awk -vFPAT='[^,]*|"[^"]*"'  'NR==1 { print; next} {print $1, $2, $3, $4, substr($5,1,5)}'

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