Files live in a large tree, the file hierarchy.
Each has a
.I "pathname"
-describing the path from the root of the tree (which is called /)
+describing the path from the root of the tree (which is called
+.IR / )
to the file.
-For example, such a full pathname might be /home/aeb/tel.
+For example, such a full pathname might be
+.IR /home/aeb/tel .
Always using full pathnames would be inconvenient, and the name
of a file in the current directory may be abbreviated by giving
only the last component.
-That is why "/home/aeb/tel" can be abbreviated
-to "tel" when the current directory is "/home/aeb".
+That is why
+.I /home/aeb/tel
+can be abbreviated
+to
+.I tel
+when the current directory is
+.IR /home/aeb .
.LP
The command
.I pwd
(with a rather baroque syntax) will find files with given name
or other properties.
For example, "find . \-name tel" would find
-the file "tel" starting in the present directory (which is called ".").
+the file
+.I tel
+starting in the present directory (which is called
+.IR . ).
And "find / \-name tel" would do the same, but starting at the root
of the tree.
Large searches on a multi-GB disk will be time-consuming,