One of my colleague ran into trouble with setting up of path variable.
Earlier the entry for PATH in /etc/profile was:

Now what he mistake is:
He added a new Lines at the end as

Now due to this he is unable to run commmands now because that has overwritten the earlier PATH varaible.
If he types now:

echo $PATH
It shows:
How Can he get rid of the same?

From the command line, you can reset the path.

Then you can edit /etc/profile and fix the problem.

It's easy to correct.

Su to root, then issue this command:
export PATH=/usr/local/bin:/bin:/usr/bin:/home/myname/bin:/sbin


That should overwrite the current PATH variable.

The lines shown would not change the value of PATH. When you wrote "He added a new Lines at the end as", where did he write the new lines, at the end of what?

Perhaps the mistake was to add new lines If so, neonsignal's technique can be used to fix the error in the changed file.

I think that re-booting resets the PATH variable---If you rummage around in the startup scripts, you will see various places where PATH is set.

Why does the new line entry:

eliminated the earlier line PATH variable.
Does it read line by line.

Pixellany is certainly correct in post #5 -- rebooting will bring the path back to normal. You might also try going to init level 1, and back again to whatever runlevel you are at now. That should fix it too. Or, try sourcing /etc/profile or whatever is the equivalent file on the system in question.

Note: In your first post, you wrote that your friend (or whoever) did the following:

LD_LIBRARY=/opt/tptp/linux_em94/bin
export PATH

And then his $PATH showed this:

/opt/tptp/linux_em94/bin

But something is amiss there; If the above is what he did, then $PATH would be empty. Perhaps you omitted a step?

In any event, if you (re)define a common environment variable, and then export it, it becomes part of that shell's environment. But it is only 'temporary'-- it isn't a permanent change to the system. You could say PATH="ogopogo and orange juice" end export it, and your path would be just that, until you exit that shell and/or reset the path and/or reboot.

Of course, if he edited /etc/profile and made a silly path in there, all that need be done is to fix that file, and reboot (or maybe go to init 1 and back to init 3/4/5) and it will be fixed.

PS - Yes, it reads line by line. So if you set PATH 5 times in a row, it will be overwritten (reset) each time, and will only end up containing the most recent bunch of items. This is why, when ADDING stuff to a PATH, we usually do:
PATH="$(PATH}:/new/entry:/more/stuff:/bin/weird/location:." so that the NEW stuff gets added to the already existing stuff.

Sasha

The second assignment overwrites the first one in /etc/profile. It should have been: