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--- bash:redirection [2019/12/14 19:40] – peter
+++ bash:redirection [2021/01/13 21:51] (current) – [BASH - Redirection] peter
@@ Line 1: / Line 1: @@
 ====== BASH - Redirection ======
-Each file in Linux has a corresponding File Descriptor associated with it.
+In Linux/Unix, everything is a file.  Regular file, Directories, and even Devices are files.
+Every File has an associated number called File Descriptor (FD).
+  * Your screen has a File Descriptor.  When a program is executed the output is sent to File Descriptor of the screen, and you see program output on your monitor.
+  * Your printer has a File Descriptor.  If the output is sent to File Descriptor of the printer, the program output would be printed.
+----
+===== Standard File Descriptors =====
+Whenever you execute a program/command at the terminal, 3 files are always open, viz., standard input, standard output, standard error.
+These files are always present whenever a program is run.
+^File^File Descriptor^
+|Standard Input STDIN|0|
+|Standard Output STDOUT|1|
+|Standard Error STDERR|2|
 The keyboard is the standard input device while your screen is the standard output device.
-Summary:
+However, files can have their input and output redirected, using:
-  * ">" is the output redirection operator. ">>" appends output to an existing file
+  * ">" is the output redirection operator.
+  * ">>" appends output to an existing file
   * "<" is the input redirection operator
   * ">&" re-directs output of one file to another.
   * Errors can be re-directed using its corresponding File Descriptor 2.
 ----
@@ Line 51: / Line 71: @@
 ===== Input redirection =====
-The '<' symbol is used for input(STDIN) redirection.
+The '<' symbol is used for input (STDIN) redirection.
 <code bash>
@@ Line 61: / Line 81: @@
 ----
-===== File Descriptors (FD) =====
+===== Error Redirection =====
-In Linux/Unix, everything is a file.
-Regular file, Directories, and even Devices are files.
-Every File has an associated number called File Descriptor (FD).
-Your screen also has a File Descriptor.
-When a program is executed the output is sent to File Descriptor of the screen, and you see program output on your monitor.
-If the output is sent to File Descriptor of the printer, the program output would have been printed.
-----
-==== Error Redirection ====
-Whenever you execute a program/command at the terminal, 3 files are always open, viz., standard input, standard output, standard error.
-----
-These files are always present whenever a program is run.
-As explained before a file descriptor, is associated with each of these files:
-^File^File Descriptor^
-|Standard Input STDIN|0|
-|Standard Output STDOUT|1|
-|Standard Error STDERR|2|
-By default, error stream is displayed on the screen.
-Error redirection is routing the errors to a file other than the screen.
-==== Why Error Redirection? ====
 Error re-direction is one of the very popular features of Unix/Linux.
@@ Line 107: / Line 92: @@
 The solution is to re-direct the error messages to a file.
-=== Example 1 ===
+==== Example 1 ====
 <code bash>
@@ Line 123: / Line 108: @@
 ----
-=== Example 2 ===
+==== Example 2 ====
-Here is another example which uses find statement -
 <code bash>