8.11 sort_wc_uniq command
8.12 tee_tr_split command
8.13 Under special shell symbols
shell special symbol cut command
*any arbitrary character -- wildcard
? any character
#comment characters
\ escape character
|pipe
cut command: used to intercept a field or character
-d: delimiter -f specifies the segment number -c specifies the number of characters
Command format: cut -d ':' -c/f n {n is a number} Note: Represents the number of blocks and the number of characters to be split
Example: -f usage
-c usage:
sort: used for sorting
-n: use pure numeric sorting (special symbols will start with the number 0)
-r: sort in reverse order
-d: split character, sort by split character
wc command:
wc -l : count the number of lines
wc -m: count the number of characters (including hidden $)
wc -w: count the number of words
wc does not follow anything: count the number of lines, characters and words
uniq: You must sort first to remove duplicates
Command format: uniq
-c: count the number of duplicate rows, the premise must be sorted first
tee：
tee -a: added
Similar to redirect>, it will be displayed on the screen when the file is written to the following document
tr: used to replace characters
Command format:
Replacement characters: tr '[aZ]''[ZA]'-----Comment: Specify the range
Replace a single character tr 'rR' Comment: Specify a single character
-d: delete a character
split: cut
Command format: split option filename
-b: Split documents by size:
-l: split the document by the number of lines
Under shell special symbols:
$variable prefix------! $combination, execute the previous variable
; Write multiple commands on one line, use ; to indicate
~User home directory
& put after the command, it will drop the command to the background
[ ] specifies one of the characters, such as [0-9]
||: For example, cat /etc/fstab||wc -l----When cat is executed successfully, wc will not be executed, and if it fails, touch will be executed
&&: For example: wc-l && cat Cat can only be executed after wc is executed successfully
