CODEWITHSUNDEEP
linuxbasharguments
Barney Chambers
Barney Chambers

Reputation: 2783

Bash, print 0 in terminal each time a non recognised argument is input

I have a bash program which extracts marks from a file that looks like this:

 Jack ex1=5 ex2=3 quiz1=9 quiz2=10 exam=50

I want the code to execute such that when I input into terminal:

./program -ex1 -ex2 -ex3

Jack does not have an ex3 in his data, so an output of 0 will be returned:

Jack 5 3 0

how do I code my program to output 0 for each unrecognized argument?

Upvotes: 0

Views: 43

Answers (1)

David C. Rankin
David C. Rankin

Reputation: 84561

If I understand what you are trying to do, it isn't that difficult. What you need to do is read each line into a name and the remainder into marks. (input is read from stdin)

Then for each argument given on the command line, check if the first part matches the beginning of any grade in marks (the left size of the = sign). If it does, then save the grade (right side of the = sign) and set the found flag to 1.

After checking all marks against the first argument, if the found flag is 1, output the grade, otherwise output 0. Repeat for all command line arguments. (and then for all students in file) Let me know if you have questions:

#!/bin/bash

declare -i found=0                  # initialize variables
declare -i grade=0

while read -r name marks; do        # read each line into name & marks
    printf "%s" "$name"             # print student name
    for i in "$@"; do               # for each command line argument
        found=0                     # reset found (flag) 0
        for j in $marks; do         # for each set of marks check for match
            [ $i = -${j%=*} ] && { found=1; grade=${j#*=}; } # if match save grade
        done
        [ $found -eq 1 ] && printf " %d" $grade || printf " 0" # print grade or 0
    done
    printf "\n"                     # print newline
done

exit 0

Output

$ bash marks_check.sh -ex1 -ex2 -ex3 < dat/marks.txt
Jack 5 3 0

Upvotes: 2

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