How to add a header to awk output? - linux

Question

I have a csv file that looks like below
"10.8.70.67","wireless",,"UTY_07_ISD",,26579
"10.8.70.69","wireless",,"RGB_34_FTR",,19780
I want to retrieve first, second and fourth column values (without quotes) and populate into a another csv in the below format.
IP DEVICETYPE DEVICENAME
10.8.70.67 wireless UTY_07_ISD
10.8.70.69 wireless RGB_34_FTR
I have used the below awk command
awk -F ',|,,' '{gsub(/"/,"",$1); gsub(/"/,"",$2); gsub(/"/,"",$3); print $1, $2, $3}' file.csv
and got the below output
10.8.70.67 wireless UTY_07_ISD
10.8.70.69 wireless RGB_34_FTR
please help in assigning headings to each column.

Answer 1

assuming you don't have comma or double quotes in the quoted strings (a big assumption!) it can be as simple as
$ awk -F, 'NR==1 {print "IP","DEVICETYPE","DEVICENAME"}
{gsub(/"/,"");
print $1,$2,$4}' file | column -t
IP DEVICETYPE DEVICENAME
10.8.70.67 wireless UTY_07_ISD
10.8.70.69 wireless RGB_34_FTR

Answer 2

With your shown samples, could you please try following. Written and tested in GNU awk.
awk -v FPAT='([^,]*)|("[^"]+")' '
BEGIN{
OFS=","
print "IP DEVICETYPE DEVICENAME"
}
function remove(fields){
num=split(fields,arr,",")
for(i=1;i<=num;i++){
gsub(/^"|"$/,"",$arr[i])
}
}
{
remove("1,2,4")
print $1,$2,$4
}
' Input_file
Explanation: Adding detailed explanation for above.
awk -v FPAT='([^,]*)|("[^"]+")' ' ##Setting FPAT to get only matched fields only as ([^,]*)|("[^"]+") as per samples.
BEGIN{ ##Starting BEGIN section of this program from here.
print "IP DEVICETYPE DEVICENAME" ##printing header here.
}
function remove(fields){ ##Creating function named remove here where we are passing field numbers from where we need to remove "
num=split(fields,arr,",") ##Splitting fields into arr here.
for(i=1;i<=num;i++){ ##Traversing through all items of arr here.
gsub(/^"|"$/,"",$arr[i]) ##Globally substituting starting and ending " in mentioned fields with NULL here.
}
}
{
remove("1,2,4") ##Calling remove here with field numbers of 1,2 and 4 which we need as per output.
print $1,$2,$4 ##Printing 1st, 2nd and 4th field here.
}
' Input_file ##Mentioning Input_file name here.

Answer 3

A simple oneliner will be:
awk -F ',|,,' 'BEGIN {format = "%-20s %-20s %-20s\n"; printf format, "IP", "DEVICETYPE", "DEVICENAME"} {gsub(/"/,"",$1); gsub(/"/,"",$2); gsub(/"/,"",$3); printf format, $1, $2, $3}' abc.csv
Here I have used BEGIN/END special pattern, which is used to do some startup or cleanup actionn, to add headings. For more details please refer to the documentation Using BEGIN/END

Answer 4

I got the expected output with the below command
awk -F ',|,,' 'BEGIN {print "IP,DEVICETYPE,DEVICENAME"} {gsub(/"/, "", $1); gsub(/"/, "", $2); gsub(/"/, "", $3); print $1","$2","$3}' input.csv > output.csv
I found that I was missing BEGIN part. Thanks all for your response.