I want to use sed to add some columns into the below csv file with default value.
My file is like:
40,2012-05-30,London,61,Sunny
41,2012-02-22,Moscow,11,Snow
54,2012-04-10,Tokyo,02,Sunny
I want the output to be:
40,2012-05-30,NULL,London,NULL,NULL,61,Sunny,Tom
41,2012-02-22,NULL,Moscow,NULL,NULL,11,Sunny,Tom
54,2012-04-10,NULL,Tokyo,NULL,NULL,02,Sunny,Tom
What are the best sed or awk commands to get the desired output?
$ awk '{print $1,F,$2,F,F,$3,$4,$5,"Tom"}' FS=, OFS=, F='NULL' file
40,NULL,2012-05-30,NULL,NULL,London,61,Sunny,Tom
41,NULL,2012-02-22,NULL,NULL,Moscow,11,Snow,Tom
54,NULL,2012-04-10,NULL,NULL,Tokyo,02,Sunny,Tom
This is a series of sed commands based on the examples here:
s/31,/31,NULL,/;
s/,01/NULL,NULL,01/;
s/.$/,Tom/
As for awk, maybe you could insert the fields first and update them later:
BEGIN { FS="," }
{ print $1","$2",NULL,"$3",NULL,NULL,"$4","$5",Tom" }
If you're just adding the fields you show then something like this is fine:
$ awk 'BEGIN{FS=OFS=","} {$3="NULL,"$3",NULL,NULL"; $0=$0",Tom"} 1' file
40,2012-05-30,NULL,London,NULL,NULL,61,Sunny,Tom
41,2012-02-22,NULL,Moscow,NULL,NULL,11,Snow,Tom
54,2012-04-10,NULL,Tokyo,NULL,NULL,02,Sunny,Tom
but if you're doing more than that then there's probably a better solution for that involving shifting fields and looping through the result populating empty fields with "NULL".
sedcommand is probably not going to be enough to add all those fields to your CSV.