03- Linux directory and file Advanced Operation

Lesson advanced directories and files operations

cat (output file contents all at once)
   CAT -n filename line number
   cat -b file name is not blank line line number

less (page display, can flip up and down, up and down cursor keys key, PageUp PageDown)
   less -N file name display line numbers

tail (from the end of the file is displayed, the default is 10 lines)
   tail - specify the file name shows how many digital lines
   tail -f filename continued to display dynamic update file, l such as log content increased

head (from the beginning of the file is displayed, the default is 10 lines)
   head - digital display file names specifies how many lines
   
   
ls (see the contents of the current directory)
   LS -a show all files
   ls -l displays detailed information about a file or directory
   
wildcard : allows the user to select the file name according to the character mode.
(1) wild card is processed by the shell
(2) role is to provide some special characters to help make quick or screening a set of file names
(3) with the file name associated command often use the wildcard ls find cp mv
 
 character mode:
 * matches any number of characters (zero or more)
 ? Match any single character (placeholders)
 [] matches any character belonging to a character set
 {} string matches any one of a set of strings belongs, among a string "," partition
 
created file or directory
 touch a. txt (empty file)
 b.txt vi
 mkdir abc
 mkdir -pa / ab / abc / ABCD

cp copy files, copy files or directories to where the requirements of the original file or directory exists, the target path exists
   path can be an absolute path can also use relative paths
   can copy more than at the same time a file or directory, wildcards can be used
   under the same directory and is backed renaming
   cp -p backup configuration files used to
   replicate directory -R & lt CP
   
   
   
Music Videos cutting and pasting
   the file to the same directory for mv f1 f2 is renaming
   for folders or directory for mv d1 d2 operate under the same directory folder,
   if there is no d2 is renamed, if there is d2, d1 is to cut to the next d2
   
soft links and hard links to
   soft links are pointing to the file name, similar to Windows shortcuts
   hard link pointing to the inode number of the file system, innode related to the physical address
   
command to find:   
    Which command is a command to find the existence of, and the storage location where the command
    whereis command searches only binary files (parameter -b), man Description file (parameter -m) and source code files (parameter -s). If the parameter is omitted, all the information is returned.
    xxd view binary
    
    
file viewer:
    the Find is the most common and most powerful Find command. It can be done in real-time locate, pinpoint, but slower.
    find [specified directory] [targeting criteria]
    The -type
    -name
    -user
    -group
    -perm
    -ctime -n -n + n is less than n days, + n is n days ago
    -mtime
    -atime
    

text keyword search:
    grep text search is a powerful tool that use regular expressions to search text, and print out the matching rows
    (1) to pay attention to keyword search case sensitive
    (2) grep command supports regular expressions, regular expressions define matching rules, the wildcard function is similar, but the wildcard is shell supports.
    (3) current need only be concerned with "^ abc" beginning with "abc $" to the end of the regular expression
    (4) regular expression. Represent any one character, * means to repeat the previous character zero or more times as ooo * represents the string if it contains two or more o string
   
    number matches the number of rows grep -c
    grep -i case-insensitive
    grep -n show line numbers match and the content
    grep -v Invert
    grep -F patten non-specified regular expression
    
    
content of the document statistics:
    WC the -l / ECT / password file how many lines
    wc -c / ect / password file how many bytes
    
to view the catalog space using
    du -sh the size of files and directories
    du -ah size of all files and directories
    df -h disk space usage
    
    
delimited file:
   Split -b numbers separated by file size
   split -l numbers separated by number of lines in the file
   
merge file:
   CAT abc * >> abc.txt