在Unix中使用SED / AWK将数据附加到特定的行号

Question

I have a file separated by colons that looks like this..

StudentID:LastName:FirstName: 0962344:Bob:Billy: 0123456:Joe:Black: 0987654:Jess:Foo:

The first line will always contain the header. Let's say each field after the 3rd in all rows will contain grades.

Let's say I add hw1 to only Joe Black since he completed it early.

StudentID:LastName:FirstName:hw1: 0962344:Bob:Billy:: 0123456:Joe:Black:100: 0987654:Jess:Foo::

First Question)

How would I append to the end of the a line when I have the line number to certain lines, or append to all lines but with different data (colons, the grade, or the assignment as above)?

Second Question)

How would I add data into those newly created fields for the other students. Add the grade for hw1 for Bob and Jess if there are more grades in the file. ex..

StudentID:LastName:FirstName:hw1:hw2: 0962344:Bob:Billy:HOW DO I ADD HERE:50: 0123456:Joe:Black:100:50: 0987654:Jess:Foo:AND HERE:50:

I'm assuming I can only use Awk since sed will go through every line.

Answer 1

gawk

question 1:

 awk -F':' -vOFS=':' '{NF+=1}NR==1{$(NF-1)="hw1"}/Joe/{$(NF-1)=100}1' file
StudentID:LastName:FirstName:hw1:
 0962344:Bob:Billy::
 0123456:Joe:Black:100:
 0987654:Jess:Foo::

question 2:

awk -F':' -vOFS=':' 'NR==1{for(i=0;++i<=NF;)if($i=="hw1")l=i}/Bob/{$l="Your Num"}/Jess/{$l="Your New Num"}1' file
StudentID:LastName:FirstName:hw1:hw2:
 0962344:Bob:Billy:Your Num:50:
 0123456:Joe:Black:100:50:
 0987654:Jess:Foo:Your New Num:50:

Answer 2

You can do it without awk. When data is stored in the file input, you can loop over different lines with while read -r fields; do .. done < input while read -r fields; do .. done < input . Using a colon as a fieldsep is done with IFS=: .
The logic within the loop can be edited (I would call a function), for avoiding to much nested if-statements I used a continue for the header line.

while IFS=: read -r StudentID FirstName LastName garbage; do
        if [ "$StudentID" = "StudentID" ]; then
                echo "StudentID:FirstName:LastName:hw1:"
                continue
        fi
        if [ "${FirstName}" = "Joe" ] && [ "${LastName}" = "Black" ] ; then
                echo "${StudentID}:${FirstName}:${LastName}:100:"
        else
                echo "${StudentID}:${FirstName}:${LastName}::"
        fi
done < input > input2

I wrote the output to input2, since that wil be the input for question 2.
Just for the fun of calculating a gave Billy the value 100 / 4. Jess is lucky, he gets 100 !

while IFS=: read -r StudentID FirstName LastName hw1 garbage; do
        if [ "$StudentID" = "StudentID" ]; then
                echo "StudentID:FirstName:LastName:hw1:hw2:"
                continue
        fi
        if [ "${FirstName}" = "Bob" ] && [ "${LastName}" = "Billy" ] ; then
                (( newnumber = 100 / 4 ))
                echo "${StudentID}:${FirstName}:${LastName}:${newnumber}:50:"
        elif [ "${FirstName}" = "Not" ] && [ "${LastName}" = "Existing" ] ; then
                echo "${StudentID}:${FirstName}:${LastName}:77:50:"
        elif [ -n "${hw1}" ]; then
                echo "${StudentID}:${FirstName}:${LastName}:${hw1}:50:"
        else
                echo "${StudentID}:${FirstName}:${LastName}:100:50:"
        fi
done < input2