Importance of .profile file and a sample

What is a .profile and why do you need it?

.profile is an important file in your home directory that helps in customizing your environment. This is a file of shell commands, also called a shell script, that the Korn shell reads and runs whenever you log in to your system. This .profile along with your environment file are sources of customizing your environment.


A Sample .profile file:
#!/bin/ksh

set +u
PATH=/bin:/usr/local/bin:/usr/bin:/usr/sbin:$PATH:/etc:/usr/ucb::/usr/bin/X11:/sbin:opt/FXboks/bin

export PATH

export HOME=/optware/oracle

TERM=xterm
export TERM
EDITOR=vi
export EDITOR
# export TMOUT=0
# readonly TMOUT


#########################
# Set up shell environment:
#########################
set -u # error if undefined variable.
trap "echo 'logout'" 0 # what to do on exit.
PS1='$LOGNAME'"@"`hostname -s`"["'$ORACLE_SID'"] "'$PWD'" => "

########################
# Setup Aliases
#########################
alias l='ls -al'
alias ll='ls -al'
alias lt='ls -altr'
alias lll='ls -al|pg'
alias ldt='ls -lt|pg'
alias Grep=grep
alias tohome='cd /dbms/oracle/local/DEMO/etc'
alias tohomec='cd /dbms/oracle/local/DEMO/etc'
alias torman='cd /backup/DEMO/rman'
alias todb='cd /optware/oracle/DEMO'

########################
# Setup Default ORACLE SID
#########################

export ORACLE_SID=DEMO
export ORACLE_TERM=vt100

ORAENV_ASK=NO
. oraenv
ORAENV_ASK=YES

AIXTHREAD_SCOPE=S
export AIXTHREAD_SCOPE

TNS_ADMIN=/dbms/oracle/tnsadmin
export TNS_ADMIN

if [ -s "$MAIL" ] # This is at Shell startup. In normal
then echo "$MAILMSG" # operation, the Shell checks
fi # periodically.

. /dbms/oracle/local/dbms_local.env
set -o vi
stty erase ^?