Linux cut, awk, grep, sed

Cut is a selection command that analyzes a piece of data and takes out what we want. In general, the selection of information is usually for "line" for analysis, not the entire information analysis

Cut [-bn] [file] or cut [-c] [file] or cut [-DF] [file]

The UT command cuts bytes, characters, and fields from each line of the file and writes those bytes, characters, and fields to standard output.
If you do not specify a File parameter, the Cut command reads standard input. One of the-B,-C, or-f flags must be specified.

Main parameters
-B: split in bytes. These byte locations will ignore multibyte character boundaries unless the-n flag is also specified.
- C: split in characters.
- D: custom delimiter, default is tab.
- F: used with-D to specify which area to display.
- N: cancels splitting multibyte characters. Used only with the-B flag. If the last byte of the character falls within the range of <br/> indicated by the List parameter of the-B flag, the character will be written out; otherwise, the character will be excluded.

The cut command mainly accepts three positioning methods:

First, byte (bytes), with option-B

Second, character (characters), with option-C

Third, domain (fields), with option-f

-B supports the notation of form 3-5, and multiple positions are separated by commas.

Who|cut-b 3-5,8

Cat/etc/passwd|head-n 5|cut-d:-F 1

Use-D to set the delimiter as a colon, and then use-F to set the first domain I want to take, and then press ENTER, all the usernames are listed.

Awk

awk usage: awk ' pattern {action} ' awk is for each row, so it is hard escaped in the unit of behavior, "soft escape" can only escape some meta-characters, \ can escape some metacharacters and wildcards

variable name meaning
ARGC Command Line arguments
ARGV command-line array of elements
FileName current Input file name
FNR the record number in the current file
FSEnter the field delimiter, which defaults to a space
RS Input Record delimiter
NF number of fields in the current record
NR Record Count so far
OFSOutput field delimiter
ORS Output Record delimiter

1. The awk '/101/' file displays a matching line containing 101 of the files.
awk '/101/,/105/' file
awk ' $ = = 5 ' file
awk ' $ = = ' CT ' file note must be enclosed with double quotes
Awk ' $ * $ >100 ' file
awk ' $ >5 && $2<=15 ' file

2. awk ' {print nr,nf,$1, $NF,} ' file displays the current record number, number of fields, and the first and last fields of each row of the files.
awk '/101/{print $1,$2 + ten} ' file displays the first to second field plus 10 of the matching line of the files.
awk '/101/{print $1$2} ' file
awk '/101/{print $ A} ' file displays the first to second field of a matching row of file files, but there is no delimiter in the middle of the display.

3, DF | awk ' $4>1000000 ' obtains input through pipe breaks, such as: Displays rows where the 4th field satisfies a condition.

4, awk -f  "|"   ' {print $1} '    file         according to the new delimiter ' | ' to operate.  
   awk   ' begin { fs= "[:  \t|]"  } 
   {print $1,$2,$3} '        file          by setting the input delimiter (fs= "[:  \t|]" ) to modify the input delimiter.  

   sep= "|" &NBSP
   awk -F  $Sep   ' {print $1} '   file   According to the environment variable Sep value as the delimiter.     
   awk -F  ' [ :\t|] '   ' {print $1} '  file   is delimited by the value of a regular expression, which represents a space,:, TAB, | And as a delimiter. &NBSP
   awk -F  ' [] '      ' {print $1} '  file    follows the value of the regular expression as a delimiter, which represents [,]

5, awk-f awkfile file through the contents of awkfile files in turn control.
Cat Awkfile
/101/{print "\047 hello! \047 "}--print ' hello! after encountering a matching line  ‘. \047 represents single quotation marks .
{Print $1,$2}-Prints the first two fields of each row because there is no mode control.

6. awk ' $ ~/101/{print $} ' file displays the row (record) of the first field in the document that matches 101.

7. awk ' BEGIN {ofs= '% '}
{print $1,$2} ' file modifies the output format by setting the output delimiter (ofs= "%").

8, awk    ' begin { max=100 ;p rint  "max="  max}             BEGIN  Represents an operation that is performed before any rows are processed.  
   {max= ($1 >max ?$1:max);  print $1, "Now max is   "Max}"  file           gets the maximum value of the first field in the file.  
    expression 1? expression 2: Expression 3  equivalent to:  
   if  (expression 1)  
        expression 2 
   else 
         expression 3 
   awk  ' {print  ($1>4 ?  high  "$1: " low  "$"} '  file 

9. awk ' $ * $ >100 {print $} ' file displays the first field in the file that matches 101 of the row (record).

10. awk ' {$ = = ' Chi ' {$ = ' China '; print} ' file replaces the 3rd field and then displays the row (record) after it finds a matching row.
awk ' {$7%= 3; print $7} ' file will divide the 7th field by 3 and assign the remainder to the 7th domain and reprint.

11. awk '/tom/{wage=$2+$3; printf wage} ' file finds a matching row and assigns a value to the variable wage and prints the variable.

12. awk '/tom/{count++;}
End {print "Tom was found" count "Times"} ' file end means that processing is done after all input lines have been processed.

13. awk ' Gsub (/\$/, ""), Gsub (/,/, ""); cost+=$4;
END {print "The total is $" cost> "filename"} ' file Gsub function replaces $ with an empty string and outputs the result to filename.
1 2 3 $1,200.00
1 2 3 $2,300.00
1 2 3 $4,000.00

awk ' {gsub (/\$/, ""); Gsub (/,/, "");
if ($4>1000&&$4<2000) c1+=$4;
else if ($4>2000&&$4<3000) c2+=$4;
else if ($4>3000&&$4<4000) c3+=$4;
else c4+=$4; }
END {printf "c1=[%d];c2=[%d];c3=[%d];c4=[%d]\n", c1,c2,c3,c4} "' File
Completion of conditional statements by if and else if

awk ' {gsub (/\$/, ""); Gsub (/,/, "");
if ($4>3000&&$4<4000) exit;
else c4+=$4; }
END {printf "c1=[%d];c2=[%d];c3=[%d];c4=[%d]\n", c1,c2,c3,c4} "' File
Exits on a condition by exit, but the end operation is still performed.
awk ' {gsub (/\$/, ""); Gsub (/,/, "");
if ($4>3000) next;
else c4+=$4; }
END {printf "c4=[%d]\n", C4} "' File
The row is skipped on a condition by next, and the action is performed on the next line.


14, awk ' {print filename,$0} ' file1 file2 file3>fileall file1, file2, file3 file contents are written in Fileall, in the format of
Prints the file and the predecessor file name.

15. awk ' $1!=previous {close (previous); previous=$1}
{Print substr ($0,index, "" ") + 1) >$1} ' Fileall re-split the merged file into 3 files. and consistent with the original document.

16. awk ' BEGIN {' Date ' |  Getline D; Print D} ' sends the execution result of date to getlineby pipe, assigns the variable d, and prints.

17. awk ' BEGIN {System ("echo \" Input your Name:\\c\ "");GetlineD;print "\nyour name is", D, "\b!\n"} '
PassGetlineThe command interactively enters name and displays it.
awk ' BEGIN {fs= ': "; WhileGetline< "/etc/passwd" >0) {if ($1~ "050[0-9]_") print "}} '
Print the user name in the/etc/passwd file that contains the 050x_ user name.

18. awk ' {i=1;while (I&LT;NF) {print NF, $i; i++}} ' file implements looping through a while statement.
awk ' {for (i=1;i<nf;i++) {print NF, $i}} ' file implements loops through a for statement.
Type file|awk-f "/" '
{for (i=1;i<nf;i++)
{if (i==nf-1) {printf "%s", $i}
else {printf "%s/", $i}} ' shows the full path of a file.
Display dates with for and if
awk ' BEGIN {
for (j=1;j<=12;j++)
{flag=0;
printf "\n%d month \ n", J;
for (i=1;i<=31;i++)
{
if (j==2&&i>28) flag=1;
if (j==4| | j==6| | j==9| | j==11) &&i>30) flag=1;
if (flag==0) {printf "%02d%02d", j,i}
}
}
}‘

19. Calling system variables in awk must be in single quotation marks, or in double quotes, to indicate a string
Flag=abcd
awk ' {print ' $Flag '} ' result is ABCD
awk ' {print ' $Flag '} ' result is $flag

===============================

$awk ' begin{total=0}{total+=$4}end{print total} ' a.txt-----sum the fourth field of the A.txt file!

• $ awk '/^ (no|so)/' test     -----Print all lines that begin with mode no or so.

• $ awk '/^[ns]/{print $ ' test      -----Print this record if the record starts with N or S.

• $ awk ' $ ~/[0-9][0-9]$/(print $ ' test        ----- This record is printed if the first field ends with two digits.

• $ awk ' $ = = | | $ < test     -----If the first or equal to 100 or the second field is less than 50, the line is printed.

• $ awk ' $ = test   -----If the first field is not equal to 10, print the line.

• $ awk '/test/{print $ test -----If the record contains a regular expression test, the first field is added 10 and printed out.

• $ awk ' {print ($ > 5? "OK" $: "Error" ($)} ' test  -----If the first field is greater than 5, the expression value after the question mark is printed, otherwise the expression value after the colon is printed.

• $ awk '/^root/,/^mysql/' test       ---- Prints all records in the range of records that begin with the regular expression "root" to the record beginning with the regular expressions. If a record of the beginning of a new regular expression root is found, continue printing until the next record begins with the regular expression MySQL, or to the end of the file.

Linux cut, awk, grep, sed