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I have a set of csv files, and for each file, the first line contain field names for a data set. Some csv files have all upper case for the field names, others have all lower case for the field names. My question is how do I change every csv file so that the first line of each file (aka the field names) displays as all uppercase strings in each column?

Examples:
Dataset1.csv

a b c
x x x

Dataset2.csv

A B C
y y y

How do I make Dataset1.csv look like the following?

A B C
x x x

It may be done with the option to Uppercase of GNU sed. In-place with the option -i:

sed -i '1s/.*/U&/' Dataset1.csv

We can do by using awk and GNU sed

Method1

awk 'NR==1(i=toupper($0));print i' Dataset1.csv ; awk 'NR >=2 print $0' Dataset1.csv

Output

A B C
x x x
z z z

Method 2

sed '1s/.*/U&/g' Dataset1.csv

Output

A B C
x x x
z z z

This is a repost from stackoverflow since someone told me my question was off-topic for the site and I got the following answers:

Considering your file ends with a newline:

head -1 Dataset1.csv | tr '[:lower:]' '[:upper:]' > Dataset1_new.csv ; tail -$(( $(wc -l Dataset1.csv | cut -d ' ' -f 8) - 1 )) Dataset1.csv > Dataset1_new.csv

head -1 Dataset1.csv | tr '[:lower:]' '[:upper:]': takes the first line of your file, transforms it to uppercase & outputs it on stdout

> Dataset1_new.csv: redirects the output to a new file called Dataset1_new.csv

tail -$(( $(wc -l Dataset1.csv | cut -d ' ' -f 8) - 1 )) Dataset1.csv: outputs the rest of the lines

> Dataset1_new.csv: again, redirects the output to our Dataset1_new.csv file

You can do it with GNU sed:

$ sed -i -e '1 s/(.*)/U1/' input.csv

You can also use awk for this purpose:

awk -i.bak 'NR==1 print toupper($0) NR>1' Dataset1.csv

Explanations:

awk will take a backup of your csv file and then for the first line (NR==1) will change the whole line $0 to uppercase then for the rest of the file (NR>1) will do its default action which is printing the line.