trjhtr

I'm using bash. I have a CSV file with two columns of data that looks roughly like this

 num_logins,day
 253,2016-07-01
 127,2016-07-02

I want to swap the first and second columns (making the date column the first one). So I tried this

awk ' t = $1; $1 = $2; $2 = t; print; ' /tmp/2016_logins.csv 

However, the results are outputting the same . What am I missing in my awk statement above to get things to switch properly?

Here you go :

 awk ' FS="," print $2 "," $1 ' sampleData.csv 

Because default delimiter is space/tab. Not comma. Taking your original code, and adding a -F, solves it.

$ awk -F, ' t = $1; $1 = $2; $2 = t; print; ' /tmp/2016_logins.csv
day num_logins
2016-07-01 253
2016-07-02 127
$

Stripping it down to $0=$2" "$11 gets same result.

$ awk -F, '$0=$2" "$11' /tmp/2016_logins.csv
day num_logins
2016-07-01 253
2016-07-02 127
$

You can do this without awk as well:

IFS=','
while read a b
do
 echo $b, $a
done <<!
num_logins,day
253,2016-07-01
127,2016-07-02
!

BTW, I used what I think is called a 'here document' (?) - that is the construction with:

....<<!
...
!

This can be replaced with:

... < /tmp/2016_logins.csv