Env settings for oracle user , when installing Oracle on linux

Question

Good Morning Oracle Experts ;
Basicallly my major subject is Electrical and Electronics
I am very new to ORACLE/LINUX [ LEARNING  ORACLE  DBA ] Technology.
I have THREE questions .. Please help me to understand oracle concepts.
QUES  1 :
i am getting confused about “setting bash_profile” and it’s contents
I googled , it said to set env variables for oracle user. Ok .
Can anyone explain clearly what exactly happens when “ setting bash_profile ” ?
MY   BASH_PROFILE SETTINGS
My  bash_profile having  following contents  :
+# Oracle Settings+
TMP=/tmp; export TMP
TMPDIR=$TMP; export TMPDIR
ORACLE_BASE=/u01/app/oracle; export ORACLE_BASE
ORACLE_HOME=$ORACLE_BASE/product/10.2.0/db_1; export ORACLE_HOME
ORACLE_SID=TSH1; export ORACLE_SID
ORACLE_TERM=xterm; export ORACLE_TERM
PATH=/usr/sbin:$PATH; export PATH
PATH=$ORACLE_HOME/bin:$PATH; export PATH
LD_LIBRARY_PATH=$ORACLE_HOME/lib:/lib:/usr/lib; export LD_LIBRARY_PATH
CLASSPATH=$ORACLE_HOME/JRE:$ORACLE_HOME/jlib:$ORACLE_HOME/rdbms/jlib; export CLASSPATH
+#LD_ASSUME_KERNEL=2.4.1; export LD_ASSUME_KERNEL+
+if [ $USER = "oracle" ]; then+
+if [ $SHELL = "/bin/ksh" ]; then+
ulimit -p 16384
ulimit -n 65536
else
ulimit -u 16384 -n 65536
fi
fi
QUES  2 :
Please  note  : This  url  says   lot of  env  variables
http://www.idevelopment.info/data/Oracle/DBA_tips/Unix/UNIX_4.shtml
2 . In my case , Why following env variables *[LD_ LIBRARY_PATH , CLASS_PATH , PATH]* are missing ?
My  pc  showing  only  four  env variables   $ env  |  grep  -e  ORA  -e  TNS
ORACLE_SID=TSH1
ORACLE_BASE=/u01/app/oracle
ORACLE_TERM=xterm
ORACLE_HOME=/u01/app/oracle/product/10.2.0/db_1
QUES 3 :
*[ LD_ LIBRARY_PATH , CLASS_PATH , PATH ]*
*Are  they  [ above mentioned  env  variables] necessary (or) not necessary for oracle DB ?*
When listing  env  variables ,  why   they  are  not  displayed  ? (anything  wrong ) ?
As  a  beginner , I expect  some  clean  technical  information    to  improve my knowledge  ..
Thanks in advance ;

Answer 1

Required Output
*$ id*
uid=502(oracle) gid=502(oinstall) groups=502(oinstall),503(dba)
*$ env | sort*
CLASSPATH=/u01/app/oracle/product/10.2.0/db_1/JRE:/u01/app/oracle/product/10.2.0/db_1/jlib:/u01/app/oracle/product/10.2.0/db_1/rdbms/jlib
COLORTERM=gnome-terminal
DBUS_SESSION_BUS_ADDRESS=unix:abstract=/tmp/dbus-s2yfterD04
DESKTOP_SESSION=default
DISPLAY=:0.0
G_BROKEN_FILENAMES=1
GDMSESSION=default
GNOME_DESKTOP_SESSION_ID=Default
GNOME_KEYRING_SOCKET=/tmp/keyring-oJUn3E/socket
GTK_RC_FILES=/etc/gtk/gtkrc:/home/oracle/.gtkrc-1.2-gnome2
HISTSIZE=1000
HOME=/home/oracle
HOSTNAME=linuxserver
INPUTRC=/etc/inputrc
LANG=en_US.UTF-8
LESSOPEN=|/usr/bin/lesspipe.sh %s
LOGNAME=oracle
LS_COLORS=no=00:fi=00:di=00;34:ln=00;36:pi=40;33:so=00;35:bd=40;33;01:cd=40;33;01:or=01;05;37;41:mi=01;05;37;41:ex=00;32:*.cmd=00;32:*.exe=00;32:*.com=00;32:*.btm=00;32:*.bat=00;32:*.sh=00;32:*.csh=00;32:*.tar=00;31:*.tgz=00;31:*.arj=00;31:*.taz=00;31:*.lzh=00;31:*.zip=00;31:*.z=00;31:*.Z=00;31:*.gz=00;31:*.bz2=00;31:*.bz=00;31:*.tz=00;31:*.rpm=00;31:*.cpio=00;31:*.jpg=00;35:*.gif=00;35:*.bmp=00;35:*.xbm=00;35:*.xpm=00;35:*.png=00;35:*.tif=00;35:
MAIL=/var/spool/mail/oracle
ORACLE_BASE=/u01/app/oracle
ORACLE_HOME=/u01/app/oracle/product/10.2.0/db_1
ORACLE_SID=TSH1
ORACLE_TERM=xterm
PATH=/u01/app/oracle/product/10.2.0/db_1/bin:/usr/sbin:/usr/kerberos/bin:/usr/local/bin:/usr/bin:/bin:/usr/X11R6/bin:/home/oracle/bin
PWD=/home/oracle
SESSION_MANAGER=local/linuxserver:/tmp/.ICE-unix/4394
SHELL=/bin/bash
SHLVL=2
SSH_AGENT_PID=4450
SSH_ASKPASS=/usr/libexec/openssh/gnome-ssh-askpass
SSH_AUTH_SOCK=/tmp/ssh-cbAqMq4394/agent.4394
TERM=xterm
TMP=/tmp
USER=oracle
_=/usr/bin/env
WINDOWID=42039592
XAUTHORITY=/home/oracle/.Xauthority