Shell Programming and Scripting

 sh ./script

tr '[:lower:]' '[:upper:]' < $file |
while IFS=: read cmd arg1 arg2 arg3; do
    case $cmd in
        ADD)  add "$arg1" "$arg2" "$arg3"
            ;;
        DELETE) delete "$arg1" "$arg2"
            ;;
        DISPLAYALL) displayall 
            ;;
        BRAND) fbrand "$arg1" 
            ;;
        PRODUCT) fproduct "$arg1"
            ;;
        *) echo "operation unknown"
            ;;
    esac
done
# this seems to be the only declaration that works in either shell

#this one gives me errors, but is apprently the right way to do it for bourne shell.
OLDIFS=$IFS
IFS=":\n"
tr '[:lower:]' '[:upper:]' < $file |
while read cmd arg1 arg2 arg3
do
    ...
    .......
    ...
done

while IFS= ...

 while IFS=: read ...

OLDIFS=$IFS
IFS=":\n"

 
 ew record added to database
 ew record added to database
 ew record added to database

# arg errors
USAGE="usage: ./a3 -d dataBaseFilename -o operationsFilename"
ERRNOARG="error:Invalid command line not enough arguments"
ERRNOFILE="error:No operations file supplied"
ERRNOREAD="error:can't read"
ERROPEMPTY="error:Operations file empty"
ERRILLOPT="illegal options:"

# opt errors
ERRNOADD="unable to add"
ADDFORMAT="add:product:brand:isle"
ERRNODEL="not deleted does not exist"
DELFORMAT="delete:product:brand"
ERRNOBRAND="brand does not exist"
ERRNOPROD="does not exist"
ERROPERATE="unknown operation"
ERREXISTS="product already exists"

# common output
RECADDED="new record added to database"
DATAEMPTY="database is empty - nothing to display"
RECDELETE=":deleted"

readonly USAGE ERRNOARG ERRNOFILE ERRNOREAD ERROPEMPTY
readonly ERRILLOPT ERRNOADD ERRNODEL ERRNOBRAND ERRNOPROD
readonly ERROPERATE ERREXISTS RECADDED DATAEMPTY RECDELETE

% cat s
puts(){ 
  printf 'the shell splits my args like this: \n'
  printf '\t\t%s\n' "$@"
  }
  
s=a:b:c ifs=$IFS IFS=: # save the current IFS and change it

puts $s

IFS=$ifs # restore default IFS  

puts $s

% sh s
the shell splits my args like this: 
                a
                b
                c
the shell splits my args like this: 
                a:b:c

% cat s
puts(){ 
  printf 'the shell splits my args like this: \n'
  printf '\t\t%s\n' "$@"
  }

s=a:b:c
  
( 
  IFS=: # inside a sub-shell because of the () 
  echo now inside ...
  puts $s

)

echo now outiside ...

puts $s

% ash s
now inside ...
the shell splits my args like this: 
                a
                b
                c
now outiside ...
the shell splits my args like this: 
                a:b:c

echo "$var"

printf '%s\n' "$var"

echo $var

OLDIFS=$IFS
IFS=":\n"

tr '[:lower:]' '[:upper:]' < $opfile |
while read cmd arg1 arg2 arg3 arg4
do
    case $cmd in
        ADD) cmdadd=`add $arg1 $arg2 $arg3 $arg4`
            ;;
        DELETE) cmddelete=`delete $arg1 $arg2 $arg3`
           ;;
        ETC) etc etc
            ;;
        *) echo "invalid"
    esac
    IFS=$OLDIFS
    #somehow execute the variable or file... maybe another case?
    IFS=":\n"
done

% uname
CYGWIN_NT-5.1
% type -a sh
sh is /usr/bin/sh
sh is /bin/sh
% /usr/bin/sh --version
GNU bash, version 3.2.49(22)-release (i686-pc-cygwin)
Copyright (C) 2007 Free Software Foundation, Inc.
% /bin/sh --version
GNU bash, version 3.2.49(22)-release (i686-pc-cygwin)
Copyright (C) 2007 Free Software Foundation, Inc.

If  bash  is  invoked  with  the name sh, it tries to mimic the startup
       behavior of historical versions of sh as  closely  as  possible,  while
       conforming  to the POSIX standard as well.  When invoked as an interac-
       tive login shell, or a non-interactive shell with the  --login  option,
       it  first  attempts  to read and execute commands from /etc/profile and
       ~/.profile, in that order.  The  --noprofile  option  may  be  used  to
       inhibit  this  behavior.  When invoked as an interactive shell with the
       name sh, bash looks for the variable ENV, expands its value  if  it  is
       defined,  and uses the expanded value as the name of a file to read and
       execute.  Since a shell invoked as sh does not attempt to read and exe-
       cute  commands from any other startup files, the --rcfile option has no
       effect.  A non-interactive shell invoked with  the  name  sh  does  not
       attempt  to  read  any  other  startup files.  When invoked as sh, bash
       enters posix mode after the startup files are read.