added redirection

Author: Pyloris

.github/workflows/mergeFiles.yml

@@ -19,7 +19,7 @@ jobs:
     - name: Merge MD Files
       run: |
         # Define the order of markdown files to merge
-        files_to_merge=("index.md", "navigation.md", "files.md", "ssh.md", "sed.md", "grep.md", "searchingFiles.md", "netstat.md", "lsof.md", "curl.md", "wget.md")
+        files_to_merge=("index.md", "navigation.md", "files.md", "ssh.md", "sed.md", "grep.md", "searchingFiles.md", "netstat.md", "lsof.md", "curl.md", "wget.md", "redirection.md")
         # remove existing contents readme
         echo '' > README.md
         # Merge files in the specified order

index.md

@@ -20,6 +20,6 @@
 
 
 ### Stuff you should to Know
-1. [Redirection](#REDIRECTION)
+1. [Redirection](#redirection)
 2. [Process Substitution](#PROCESS_SUBSTITUTION)
 3. [Bash Fu](#BASHFU)

redirection.md

@@ -0,0 +1,17 @@
+## Redirection
+
+> Redirect output to stdin of another command using `>` and to redirect standard input, we use `<`.
+```shell
+cat file.txt > file2.txt
+cat < file.txt
+# redirect stderr
+find / 2> /dev/null
+# redirect stdout and stderr
+find / 2> /dev/null 2>&1
+```
+
+> To redirect output of one command to input of another, we use piping `|`.
+```shell
+ls / | grep root
+```
+* We cannot do this using `>` because, it writes to a file descriptor and `grep` takes in a file descriptor to read from. To make it work, we may use process substitution.