Circular Shifts on Strings in Bash

Answer 1

To get you started, check out the read builtin:

while read first_word rest_of_the_line; do
    ... your code here ...
done

You also need a way to feed your input file into that loop.

Answer 2

Parameter expansion will let you carve off parts of a variable.

Answer 3

A few tidbits that should help: when you call a function with a string, the string is split into multiple arguments (the positional parameters, named $n, where n are integers starting at 1) on the characters in the variable $IFS (which defaults to spaces, tabs and newlines)

function first() {
    echo $1
}
first one two three
# outputs: "one"

$* and $@ give you all the positional parameters, in order.

Second, the special variable $# holds the number of arguments to a function.

Third, shift discards the first positional parameter and moves up all the others by one.

function tail() {
    shift
    echo $*
}

Fourth, you can capture the output of commands and functions using `...` or $(...)

rest=`tail $*`

Fifth, you can send the output of one command to the input of another using the pipe character (|):

seq 5 | sort

Answer 4

this is short demo. Go through the words, get the last word and put in front of the string. until the final string is the same as the original.

    #!/bin/bash    
    s="Software Requirements Analysis"
    org="$s"
    while true
    do
       last=${s##* } #Analysis
       front=${s% *} #Software Requirements
       s="$last $front"
       echo $s
       case "$s" in
         "$org") break;;
       esac
    done

you should be able to do the rest using a file.