AIX

# ------------------------------------------------------------------------------
# f_CheckUser                                                   check UNIX user
# ------------------------------------------------------------------------------
# Author.....: Wolf Machowitsch
# last update: 2007 05 23    by: Wolf Machowitsch
# ------------------------------------------------------------------------------
# Revision Log:
# - 0.99   2007 05 23   Original Creation
#                       users are being checked if they exist (return 0)
#                       and possible problems in creating the user (name
#                       and or UID taken, both taken by different users,
#                       all these conditions lead to non-zero return values)
#                       are propagated back.
#                       As of now only AIX and Linux are explicitly supported.
#
# ------------------------------------------------------------------------------
# Usage:
#
#     f_CheckUser char UserName int UserID
#
#     checks if a user named <UserName> and with UID <UserID> does exist. 
#
#     Example:  f_CheckUser foo 999          # checks if a user named foo
#                                            # with UID 999 does exist
#
# Prerequisites:
# -   to use this function, the FPATH variable must be set
#
# ------------------------------------------------------------------------------
# Documentation:
#     f_CheckUser() tests for the existence of UNIX-useraccounts.
#     If the user exists and is correct (correct name and UID, other
#     properties are not checked) 0 is returned.
#     If the user does not exist (meaning neither a user with that name
#     nor a user with that UID does exist) 1 is being returned. If either
#     the user name or the UID is taken by an existing user account, but the
#     respective other ingredient is not, then 2 or 3 respectively is being
#     returned. A return value of 4 is being caused by a resource conflict:
#     both name and UID are taken, but by different accounts.
#     
#     Example:
#          existing users | UID
#          foo            | 20
#          bar            | 30
#
#          f_CheckUser foo  20        # yields 0
#          f_CheckUser kuno 25        # yields 1
#          f_CheckUser foo  25        # yields 2
#          f_CheckUser kuno 20        # yields 3
#          f_CheckUser bar  20        # yields 4
#          f_CheckUser foo            # yields 5 (no second parameter)
#          
#
#     Parameters: char UserName      name of the user
#                 int  UID           ID of the user
#
#     returns:    0: user exists
#                 1: user does not exist
#                 2: user name exists but with wrong UID
#                 3: UID exists but with wrong user name
#                 4: resource conflict: UserName with different UID AND
#                                       UID with different user name
#                 5: parameter/other/internal error
#
# ------------------------------------------------------------------------------
# known bugs:
#
# -  none
# ------------------------------------------------------------------------------
# .....................(C) 2007 Wolf Machowitsch ...............................
# ------------------------------------------------------------------------------

f_CheckUser ()
{

$chFullDebug
                                                 # internal variables
typeset -i iRetVal=0                             # return value (see docu)
typeset    chUserName="$1"                       # user name
typeset -i iUID="$2"                             # UID

typeset    chNameTest=""                         # buffer f. test by name
typeset    chIDTest=""                           # buffer f. test by ID
typeset -i iErrLvl=0                             # return code buffer

if [ -n "$2" ] ; then                            # UID given ?
     iRetVal=5
fi
if [ -n "$1" ] ; then                            # name given ?
     iRetVal=5
fi

if [ $iRetVal -gt 0 ] ; then
     return $iRetVal
fi


case $OS in
     AIX)
	  chNameTest="$( \
			 lsuser -a id $chUserName 2>/dev/null |\
			 sed 's/[ 	]*id=/:/' \
		       )"
	  chIDTest="$( \
			 lsuser -a id ALL |\
			 sed -n '/id='"${iUID}"'[ 	]*$/ {
					s/[ 	]*id=/:/p
					}' \
		     )"
	  ;;

     Linux)
	  chNameTest="$( \
			  grep "^${chUserName}:" /etc/passwd |\
			  cut -d':' -f1,3 \
		       )"
	  chIDTest="$( \
			  grep "^\([^:]*:\)\{2\}${iUID}:" /etc/passwd |\
			  cut -d':' -f1,3 \
		     )"
	  ;;

     *)
	  f_CmdWarning "no explicit rule to check $OS for users"
	  chNameTest="$( \
			  grep "^${chUserName}:" /etc/passwd |\
			  cut -d':' -f1,3 \
		       )"
	  chIDTest="$( \
			  grep "^\([^:]*:\)\{2\}${iUID}:" /etc/passwd |\
			  cut -d':' -f1,3 \
		     )"
	  ;;

esac

if [ -z "$chNameTest" -a -z "$chIDTest" ] ; then
     iRetVal=1                                   # name AND UID not taken
elif [ -n "$chNameTest" -a -z "$chIDTest" ] ; then
     iRetVal=2                                   # name taken, UID not taken
elif [ -z "$chNameTest" -a -n "$chIDTest" ] ; then
     iRetVal=3                                   # name not taken, UID taken
else
					         # both name and UID taken
     if [ "$chNameTest" == "$chIDTest" ] ; then
	  iRetVal=0                              # by the same user -> ok
     else
	  iRetVal=4                              # by different users -> shit
     fi
fi

return $iRetVal

}
# --- EOF f_CheckUser