hi
if env command is given with no arguments then all the environment variables are displayed.

In which file does the environment variables are stored.

how to set and unset an environment variable

thanks

Afaik env values are stored in your computers RAM. Both variables and environment variables are variables of the shell. To make a env variable, export a normal variable, i.e.
variable="Some text"
export variable

or in one command:
export variable="some text"

they both do the same thing. To unset a variable, use unset (For both types).
unset variable

You can only unset environment variable i the active shell. Yuo will have to manually remove env variables from child shells.

(If you don't know the difference:
Normal variables are set in a shell, and are only accessible in the shell where you set it. Environment variables are inherit to newly started shells from where you set it, but you cant change nor delete any variables in other then the active shell no matter what type they are. You cant remove a env variable from the parent shell (Or an existing child shell). There are no communication between running shells. Pretty lousy explanation, I hope you understand it )

thanks for u r reply
i have understood one thing that an environment variable of one shell cant be changed by the other.

when i first log on to system and type in the shell(bash) env
i get lot of environment variables like this


e.t.c


i have searched this variables in .bash_profile and .bashrc file but i have not found any.

i just want to know from where this command picks these values and displays .

thank u

Most of it will be sourced from system-wide resource files like /etc/profile, /etc/bashrc and /etc/profile.d. Stuff like ^SSH_* is obviously set up by ssh.*. A lot of variables are not meant to be changed, so explaining what you're trying to do should get you an answer quicker.

hi
i have two accounts .in the first account when i login i get this message


the env command displays these values

e.t.c....


when i login in to the second account i dont get any error messages

and when i give the command env i get these values

e.t.c....


in this second account we can see that the PATH variable contains path for java(but not in the first account).

so where does this variable is stored .

both the accounts .bash_profile and .bashrc files are identical.


Also in the first accounts shell there is no java command and in the second account it has .

both the accounts show the same paths( java: /etc/java /usr/lib/java /usr/share/java) for the whereis java command

if i have to set these variables globally for all users what should i do .

is there any way to know the file name and its location in which a particular environment variable has been set.

thank u

if it's system-wide it should be in /etc/profile.d.

thank u

how to get rid of this error message.
-bash: export: `=/usr/java/jdk1.6.0_02': not a valid identifier
what does this error message specify.