A file descriptor is an abstract value of type Unix.file_descr,
containing information necessary to use a file: a pointer to the file,
the access rights, the access modes (read or write), the current position
in the file
or we can say
Under the covers of the Unix operating system, files are referenced, copied, and moved by unique numbers known as file descriptors.
Three descriptors are predefined. They correspond to standard input, standard output, and standard error.
0 - stdin (Standard Input) "<"
1 - stdout ( Standard Output) "1>" or ">"
2 - stderr ( Standard Error) "2>"
or we can say
Under the covers of the Unix operating system, files are referenced, copied, and moved by unique numbers known as file descriptors.
Three descriptors are predefined. They correspond to standard input, standard output, and standard error.
0 - stdin (Standard Input) "<"
1 - stdout ( Standard Output) "1>" or ">"
2 - stderr ( Standard Error) "2>"
