.env file

A fourth file that the operating system uses at login time is the .env file, if your .profile contains the following line: export ENV=$HOME/.env

The .env file lets you customize your individual working environment variables. Because the .env file is hidden, use the ls -a command to list it. For more information about the ls command, see ls. The .env file contains the individual user environment variables that override the variables set in the /etc/environment file. You can customize your environment variables as desired by modifying your .env file.

The following example is a typical .env file:

export  myid=`id | sed -n -e 's/).*$//' -e 's/^.*(//p'`
#set prompt: login & system name & path 
if [ $myid = root ]
        then    typeset -x PSCH='#:\${PWD}> '
                PS1="#:\${PWD}> "
        else    typeset -x PSCH='>'
                PS1="$LOGNAME@$UNAME:\${PWD}> "
export PS1 PS2 PS3
#setup my command aliases
alias   ls="/bin/ls -CF" \
        d="/bin/ls -Fal | pg" \
        rm="/bin/rm -i" \
        up="cd .."
Note: When modifying the .env file, ensure that newly created environment variables do not conflict with standard variables such as MAIL, PS1, PS2, and IFS.