Multithreading - Calling user function with xargs in korn shell

Shell Programming and Scripting
1

I know there are other ways of accomplishing the below task, but the purpose of this thread is to understand the below code.

I wanted to use xargs with user defined function in korn shell. Am aware, that I could write custom function into a script and place it in FPATH and then call it in xargs, but I wanted to have it all in the same shell script. Bash isnt an option for me at the moment. After 2-3 days of searching, I found the solution which works, but am unable to understand a part of it..

cat ordernum.txt | xargs -P 25 -n 1 ksh -c '
  function fun { 
    do some processing
  } 
  shift "$1" 
  fun "$@"' 2 1

Can someone help me with the last two lines of the code.

Thanks a ton.

2

shift moves the parameters so that $2 is now $1,etc.
$@

Inside double quote marks (" "), parameter and command substitution occur and \ quotes the characters \, `, ", and $. A $ in front of a double quoted string will be ignored in the "C" or "POSIX" locale, and may cause the string to be replaced by a locale specific string otherwise. The meaning of $* and $@ is identical when not quoted or when used as a variable assignment value or as a file name. However, when used as a command argument, "$*" is equivalent to "$1d $2d . . .", where d is the first character of the IFS variable, whereas "$@" is equivalent to "$1"  "$2"  . . . . Inside grave quote marks (` `), \ quotes the characters \, `, and $. If the grave quotes occur within double quotes, then \ also quotes the character ".

> cat test.sh
shift "$1"
echo "$@" 2 1

> test.sh 1 2 3 4 5 6 7 8 9
2 3 4 5 6 7 8 9 2 1

> test.sh 1
2 1

> test.sh 1 2
2 2 1
3

I was thinking, it would go into endless loop, as the function "fun" is being declared and at the end it being called as well..:confused: within the function