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Shell_ 02_ Text three swordsman
2022-07-06 16:50:00 【Coke loving w】
Shell_02_ Text three swordsman
cut
cut command : Operate on data in fields
Command format :cut Options File path
Options | meaning |
---|---|
-d | Specify the delimiter of the data |
-f | Specify the field display |
-c N | Appoint N The characters are 1 Display units |
1)-d and -f Options together make sense ( Only the delimiter of the specified data , Data can be segmented )
2)-c The value followed by the option “-” There are different meanings in different places
Such as : Show PATH The fifth path in the variable path
Such as : Display in different character units test1.txt The contents of the document
sed
sed command : Replace data in behavioral units 、 Delete 、 newly added 、 Selection and other functions
Command format :sed Options ‘ operation ’ File path
1) Options are optional , But the operation must have ;
2)sed Command more than two operations , Need to add -e Options ;
3) The operation must be enclosed in two single quotation marks , And between multiple operations “;” Separate ;
Options | meaning |
---|---|
-n | Only output is sed Processed lines |
-e | In the command prompt interface sed operation |
-f | take sed Write to a file |
-r | Use extended regular expression syntax ( The default is the basic regular expression syntax ) |
-i | Directly modify the contents of the document ( The default is to only read the file and output it to the terminal ) |
operation | meaning |
---|---|
s | Replace / Delete string ( Usually used with regular expressions ) |
y | Replace character |
i | ( Last line ) Insert |
a | ( The next line ) Insert |
c | Replacement row |
d | Delete row |
p | Print ( Usually cooperate -n Options together make sense ) |
Replace string
s operation : Replace the string specified in the data flow
1) Format :s/ Original string / New string / identification
2) Signs are divided into (p and w It can be used for other operations ):
identification | explain |
---|---|
g | All occurrences of the original string in the data stream are replaced |
p | Print out the line where the string is operated |
w File path | Write the result of the operation to the specified file |
The number N | Specify the number of... That the string successfully matches in this line N Time , To replace |
3) By default, only the first string that is successfully matched is replaced ;
4) If the new string is empty , Then you can delete the original string ;
Such as : Replace the specified string
Such as : Only print out by sed Command replacement line
Such as : adopt s Operation deletes the specified string
y operation : Replace a single character in the data stream
1) Format :y/ Original character / New character /
2) The number of original characters should be consistent with the number of new characters ;
3) By default, it works on all strings in the data flow ( The range cannot be specified by addressing )
Such as : Replace specified characters
Addressing
Row addressing (Line Addressing): Appoint sed The scope of the operation of the command line
1)sed The operation of the command works on all data lines by default ;
2) Row addressing is divided into : Digital addressing 、 Text addressing
(1) Digital addressing
1)sed By default, the row number is assigned from the first row of data 1( Including the empty line );
2) Digital addressing is divided into : That's ok 、 Row interval
3) Digital addressing format :‘ Values and operations ’
// When specifying a row interval , Use between multiple values “,” Separate ( The interval contains the value itself )
Such as : Through digital addressing , Replace specified data
(2) Text addressing
1) Select the line containing the specified string ;
2) Text addressing format :‘/ character string / operation ’
Such as : Through text addressing , Replace specified data
(3) When multiple operations are performed under the same address , Operations need to be specified by branches
// It can also be written on the same line , However, you need to specify addressing multiple times and use “;” Separation operation
Such as : In the specified row , Replace multiple data at the same time
Delete
d operation : Delete the specified row in the data flow
1) Format : Match format d
2) If no string is specified , Then the string of all lines is deleted by default ;
3) Use two text addressing , It can realize the opening and closing of the deletion function ;
// Enable the deletion function when matching to the first text addressing , Close when the second one is matched
Such as : Delete specified row
Such as : Addressing through two texts , Realize the opening and closing of the deletion function
Insert
i operation : Insert a row of data into the previous row of the specified row in the data flow
1) Format : Addressing i\ insert data
2)i Operation must be coordinated with addressing , And row interval addressing cannot be used ;
// If addressing is not specified , By default, the specified data is inserted in the previous row of all rows
3)a Operation and i Same operation ( The difference lies in : Insert );
Such as : Read data6 In the file data stream , The first 3 Insert the specified data in the previous row of the row
Replacement row
c operation : The new row replaces the specified row in the data flow
1) Format : Addressing c\ New line
2)c Operation must be coordinated with addressing ( If row interval addressing , Then the interval is replaced by a new line );
// If addressing is not specified , Replace all rows in the data flow by default
Such as : The new line replaces the specified line
gawk
gawk Program :Unix in awk programmatic GNU edition , It has the following functions
1) Variables can be defined to store data ;
2) Use arithmetic and string operators to process data ;
3) Use structured programming concepts to add processing logic to data processing ;
4) By extracting the data elements in the data file , Format it and output ;
gawk command : The fields in each row are used to replace the data 、 Delete 、 newly added 、 Selection and other functions
Command format :gawk Options ‘ key word 1{ operation 1} key word 2{ operation 2}’ File path
Options | meaning |
---|---|
-F character | Specifies the separator for the field |
-f File path | Specify storage gwak Files for operation |
-v Variable name = value | Define variables and variable values |
-mf | Specify the maximum number of processing fields in the data flow |
1)gawk Unit by behavior , Take the field as the processing unit ;
2)gwak The built-in variables for each field in are :
Variable name | explain |
---|---|
$0 | Represents the whole row of data |
$1 | On behalf of the 1 A field |
$2 | On behalf of the 2 A field |
$N | On behalf of the N A field |
3)gawk Other built-in variables
Variable name | meaning |
---|---|
NF | The total number of fields per row |
NR | gawk What line of data is being processed |
FS | Input field separator ( Default is space ) |
RS | Enter the delimiter of the data row |
OFS | Separator for output field |
ORS | Separator of output data row |
// Built in variables in gawk When used inside , There is no need to add variable symbols before “$”
4)gawk in 3 Key words :BEGIN( The first to perform )、pattern、END( Finally, execute )
// When specifying split characters , Need to use BEGIN key word , otherwise gawk When the split character has not been replaced , Other operations have already been processed
// The default is omitted pattern key word ( Use less )
Such as : Format output
// When there are multiple commands in an operation , Need to use “;” Separate
Such as : Store by calling gwak Files for operation , Output /etc/passwd The user name of the file and UID
Such as : Inquire about /etc/passwd In the file UID Less than 10 Users of , And pass awk Format output
//gawk Operation selection can be realized by logical operation , And awk and gawk Universal
Such as : adopt gawk Format output
1) To write 3.sh Script files
2) call 3.sh Script files
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