Linux Common text Operations

Cat connection file, print to standard output device

Introduction to Grammar

Cat [OPTION] ... [FILE] ...
-a--show-all equivalent to-vet
-B Display number strip blank line
-N display number includes blank line
-E Display line terminator
-s consecutive lines of whitespace, showing one row
-T Display tab
-V uses the ^ and M-symbols, in addition to LFD and TAB.

Usage scenarios:

Show line Numbers

[Email protected] ~]# cat-n anaconda-ks.cfg

Connect to view

[Email protected] ~]# cat-n anaconda-ks.cfg/etc/hosts

Merging files

[email protected] ~]# cat T1 T2 > T3

REDIRECT Text input

[[email protected] ~]# cat << EOF
Hello World
Eof
Hello World

REDIRECT File input

[email protected] ~]# Cat < anaconda-ks.cfg

More

Show files by percentage, filter, search, and more easily read large files than cat

Parameters:

-num number of rows displayed at one time
-d prompts the user to display under the screen [press space to continue, ' Q ' to quit.], if the user presses the wrong key, then it will be displayed with the message "H ' for instructions." Instead of the beep.
-l Cancel feature that pauses when meeting special character ^l (paper feed characters)
-F Number of rows, in actual number of rows, rather than lines after word wrap (some single-line words that are too long will be extended to two or more lines)
-p do not scroll to display each page, but first clear the screen and then display the content
-c similar to-p, the difference is to display the content before clearing other old data
-S When you encounter a row that has more than two consecutive lines, replace the blank line with one line
-U does not display quotation marks (varies according to the terminal specified by the term of the environment variable)
+/pattern searches for the string before each document is displayed, and then starts displaying it after the string
+num starting from Num line
FileNames to display the contents of the document, can be the number of complex

Operation Command:

Enter down n rows, which need to be defined. Default is 1 rows
CTRL+F Scroll down one screen
Space bar scroll down one screen
Ctrl+b Back to previous screen
= Output the line number of the current line
: F output File name and line number of the current line
V Call VI Editor
command to invoke the shell and execute the command
/keyword Search Keywords
Q Exit More

Common operations:

[Email protected] ~]# more-s -20 anaconda-ks.cfg

Less

More flexible than more, the mouse can scroll forward backward, casual browsing, or lazy loading, parameter usage and more similar

Common operations:

[Email protected] ~]# less-s -20 anaconda-ks.cfg

Head

View the first few lines of a file

[Email protected] ~]# head-2 anaconda-ks.cfg

Tail

View the end of the file in a few lines, as well as the monitoring file function

Parameters:

-N Display number of rows
-F Monitoring File

Common operations

[Email protected] ~]# Tail-2 anaconda-ks.cfg
[Email protected]ost ~]# tail-f anaconda-ks.cfg

Implementation of tail based on Python to view the end of the file line function

def read_last_lines (Filename,lastlines=1): F = open (filename, ' rb ') First_line_data,first_tell = F.readline (), F.tell () F.seek (0) Seek = 0 #第一层循环判断是否为空文件 for i in F:while True:f.seek (seek,2) Curre Nt_tell = F.tell () Seek-= 1 data = F.readlines () if (First_tell = = Current_tell and not D  ATA): F.close () return ' 1 ', [First_line_data] elif (First_tell = = Current_tell and Data): if (len (data) <lastlines): Data.insert (0,first_line_data) F.clos  E () return ' 2 ', Data else:if (lastlines! = 1): if (len data) = =                        Lastlines): Return ' 3 ', Data else:if (len (data) = = 1): if (First_tell = = F.tell ()): F.close () return ' 4 ', Da                 Ta[-1:]   if (len (data) > 1): F.close () return ' 5 ', data[-1:]data = read_last_l Ines (' Test2.txt ', lastlines=10) print (data)

Not to be continued ....

Linux Common text Operations