.CD "which \(en examine $PATH to see which file will be executed"
.SX "which \fIname"
.FL "\fR(none)"
.EY "which a.out" "Tells which \fIa.out\fR will be executed"
.PP
The $PATH shell variable controls the 
.MX
search rules. 
If a command \fIa.out\fR is given, the shell first tries to find an 
executable file in the working directory.  
If that fails, it looks in various system directories, such as 
\fI/bin\fR and \fI/usr/bin\fR.  
The\fR which\fR command makes the same search and gives the absolute
path of the program that will be chosen, followed by other occurrences
of the file name along the path.