System Commands OPPE 2: January 2023, Set 1 (January 2023 term)

Write a SED script to add a new column in the beginning with entry "S1" or "S2". "S1" occurs periodically every 3rd line starting from first line, while rest is "S2"

Sample Input

Ajay,Chennai,Sales,40
Mona,Mumbai,Sales,60
Rajan,Patna,Buisness,50
Narayanan,Kochi,Sales,30
Anuj,Pune,Sales,70
Mohan,Jaipur,Buisness,70
Naga,Vizag,Sales,45
Chaitrali,Nagpur,Sales,90
Sanjana,Delhi,Buisness,80
Maitreyi,Bhopal,Sales,30
Sreni,Bangaluru,Sales,20

Sample Output

S1,Ajay,Chennai,Sales,40
S2,Mona,Mumbai,Sales,60
S2,Rajan,Patna,Buisness,50
S1,Narayanan,Kochi,Sales,30
S2,Anuj,Pune,Sales,70
S2,Mohan,Jaipur,Buisness,70
S1,Naga,Vizag,Sales,45
S2,Chaitrali,Nagpur,Sales,90
S2,Sanjana,Delhi,Buisness,80
S1,Maitreyi,Bhopal,Sales,30
S2,Sreni,Bangaluru,Sales,20

Write a bash script to add serial number as first column to the CSV file data.csv and do a in-place replacement (overwrite) the file data.csv. The serial number starts with 1 on the first line.

Write a SED script to mask the first 6 digits of the phone numbers with asterisks, such that only last four digits of phone number of ten digits are visible.