SED command application

Sed:stream EDitor, row editor;

Usage: sed [option] ... ' Script ' inputfile ... script: ' Address command ' common options:-N: Do not output the contents of the schema to the screen;-e: Multi-dot
            -f/path/to/script_file: Reading an edit script from a specified file;-r: Supports the use of extended regular expressions;-I: Edit; address delimitation:
            (1) Do not address: The full text of the processing, (2) Single address: #: Specified line;/pattern/: Each row to which the pattern can be matched;
            (3) Address range: #,# #,+#/pat1/,/pat2/#,/pat1/
            (4) ~: Step 1~2 2~2 Edit command: D: Delete P: Display content in mode space A \text: Append text after line, support using \ n to implement multiline append; I \text: Insert text before line, support use \ n to implement multiple-row inserts; C \text: Replace the behavior single or multiline text; w /path/to/somefile: Saves the mode space to match the row to the specified file; R/path/from/somefile: reads the text stream of the specified file to the row in the pattern space that matches to the row; =: Hit the line in the pattern space 
            Printing line number;!: take the opposite condition;
    s///: Supports the use of other delimiters, s@@@,s###; Replace tags: g: In-line global substitution;                P: Shows the row in which the replacement succeeds; W/path/to/somefile: Saves the result of the replacement success to the specified file; Exercise 1: Delete/boot/grub/g Rub.conf a white-space character in a file that starts with a blank line at the beginning of a white space; ~]# sed ' s@^[[:space:]]\+@@ '/etc/grub2.cfg Exercise 2: Delete/etc/f The # and whitespace characters in the stab file at the beginning of the line with #, followed by at least one white-space character; ~]# sed ' s@^#[[:space:]]\+@@ '/etc/fstab practice 3:e Cho an absolute path to the SED command, take out its base name; ~]# echo "/etc/sysconfig/" |
                Sed ' s@[^/]\+/\?$@@ ' advanced Edit command: H: The content of the mode space is covered to maintain space, H: the content of the pattern space is appended to the space of keeping;
                G: From the space to retain the data coverage to the mode space, G: from the retention of space to remove the content appended to the mode space; x: The content in the mode space is exchanged with the content in the space; N: Reads the next line to the pattern space of the line that matches to; N: appends the next line of the line to the pattern space; d: Deletes the rows in the mode space; D: Deletes all in the multiline mode space line; Sed-n ' N;p ' FILE: Show even-numbered sed ' 1! G;h;$!d ' file: Reverse display of file content sed ' $! n;$!
             D ' file: Two lines after the file is fetched; sed ' $!d ' file: Take out the last line of the file;   Sed ' G ' file:sed '/^$/d; G ' file:sed ' n;d ' FILE: show odd rows; Sed-n ' 1!
 G;h $p ' file: reverse displays each row in the file;