Table of contents
2. File Operation Four Musketeers
One, regular expressions
1. Basic rules
a) Find specific characters cat test.txt | grep -n 'was'
b) Use [] to find set characters cat test.txt | grep -n 'sh[io]rt' match i or o
cat test.txt | grep - n '[^w]' Exclude w
cat test.txt | grep -n '[ah]oo'
cat test.txt | grep -n '[0-9]'
c) Find the beginning of the line "^" and the end of the line " $"
cat test.txt | grep -n '^[AZ]'
cat test.txt | grep '\.$' \ is the escape character
d) Find any character "." and repeated characters "*"
cat test. txt | grep -n 'w..d'
cat test.txt | grep -n 'ooo*'
e) To find the continuous character range "{}", need to use escape character, "\{\}"
cat test. txt | grep -n 'o\{2\}'
cat test.txt | grep -n 'wo\{2,5\}d'
cat test.txt | grep -n 'wo\{2,\}d'
2. Extended regularization
a) +, repeat one or more of the previous character
cat test.txt | grep -nE 'wo+d' or
cat test.txt | egrep -n 'wo+d'
b) ?, zero or one of the previous character Character
cat test.txt | egrep -n 'bes?t'
c)|, use or to find multiple characters
cat test.txt | egrep -n 'of|is|on'
d) (), find group characters String
cat test.txt | egrep -n 't(a|e)st'
e)()+, identify multiple repeated groups
cat test.txt | egrep -n 'A(xyz)+C'
3. Common regular expressions
3.1 Number
"^[0-9]*[1-9][0-9]*$" //Positive integer
"^((-\d+)|(0+))$" //Non-positive integer (negative integer + 0)
"^-[0-9]*[1-9][0-9]*$" // negative integer
"^-?\d+$" // integer
"^\d+(\.\d+ )?$" //Non-negative floating point number (positive floating point number + 0)
"^(([0-9]+\.[0-9]*[1-9][0-9]*)|([ 0-9]*[1-9][0-9]*\.[0-9]+)|([0-9]*[1-9][0-9]*))$” // Positive floating point number
"^((-\d+(\.\d+)?)|(0+(\.0+)?))$" // non-positive floating point number (negative floating point number + 0) "^(
- ?\d+)(\.\d+)?$” // floating point number
3.2 String
"^[AZ]+$" //A string composed of 26 uppercase English letters
"^[az]+$" //A string composed of 26 lowercase English letters
"^[A- Za-z0-9]+$” //A string composed of numbers and 26 English letters
“^\w+$” //A string composed of numbers, 26 English letters or underscores
3.3Email
"^[\w-]+(\.[\w-]+)*@[\w-]+(\.[\w-]+)+$" //email address "^([
w -.]+)@(([[0-9]{1,3}.[0-9]{1,3}.[0-9]{1,3}.)|(([w-] +.)+))([a-zA-Z]{2,4}|[0-9]{1,3})(]?)$” //Email
3.4Url
“^[a-zA-z]+://(\w+(-\w+)*)(\.(\w+(-\w+)*))*(\?\S*)?$” //url
3.5IP
“^(d{1,2}|1dd|2[0-4]d|25[0-5]).(d{1,2}|1dd|2[0-4]d|25[0-5]).(d{1,2}|1dd|2[0-4]d|25[0-5]).(d{1,2}|1dd|2[0-4]d|25[0-5])$” //IP地址
3.6Tel
/^((\+?[0-9]{2,4}\-[0-9]{3,4}\-)|([0-9]{3,4}\-)) ?([0-9]{7,8})(\-[0-9]+)?$/ //Phone number
3.7 Date verification
/^(d{2}|d{4})-((0([1-9]{1}))|(1[1|2]))-(([0-2]([1- 9]{1}))|(3[0|1]))$/ // year-month-day yyyy-MM-dd / yy-MM-dd format "^[0-9]{4}-
( (0([1-9]{1}))|(1[1|2]))-(([0-2]([0-9]{1}))|(3[0|1] ))$" // year-month-day yyyy-MM-dd format
/^((0([1-9]{1}))|(1[1|2]))/(([0-2 ]([1-9]{1}))|(3[0|1]))/(d{2}|d{4})$/ // month/day/year
2. File Operation Four Musketeers
1, advanced grep
options
-r recursively scans every file in the specified directory
-l only displays the file name matching the specified keyword, not the file content
Case
view all file names containing bash in the /etc directory
grep -rl bash /etc
2.egrep
Perfect support for regular expressions
3, find advanced
3.1 Search by permission -perm
3.2 Search by timestamp
-atime
-mtime
-ctime
3.4 -exec
find /var/spool/mail -type f -exec rm -rf {} \;
3.5 xargs
find /var/spool/mail -type f | xargs rm -rf
4，sed
4.1 Syntax
sed [option] 'operation' parameter
sed [option] -f scriptfile parameter
4.2 Options
-e: Indicates processing with specified command or script
-f: Specify script file
-h: Help
-n: Indicates only displaying the processed result
-i: Edit text file directly
-r: Support extended regular
4.3 Operation
a: Add, add the specified content in the row below the current row
c: Replace, replace the selected row
d: Delete, delete the specified row
i: Insert, insert a row above the selected row
p: Print
s: Replace, replace the specified row character
y: character conversion
5，awk
5.1 Syntax
awk option 'pattern or condition {edit command}' file1 file2 ...
awk -f script file file1 file2 ...
5.2 Options
-F specifies the delimiter for each line,
the default delimiter is space
5.3 Built-in variables
FS: specify the delimiter of each line
NF: specify the number of fields of the current processing line
NR: the line number of the current processing line
$0: the entire line content of the current processing line
$n: the nth field of the current processing
FILENAME: the processing file name
RS: data record separator, default is \n
5.4 Case
a) Output
awk '{print}' test.txt by line #equivalent to cat
awk 'NR>=1&&NR<=3{print}' test.txt
awk 'NR==1,NR==3{print}' test. txt #Print 1 to 3 lines
awk 'NR%2==0{print}' test.txt #Print even-numbered lines
b) Output by segment
defaults to "space" segment!
ifconfig ens33 |awk '/netmask/{print $2}' #filter IP address
cat /etc/shadow | awk -F : '$2=="!!"{print $1}' #print users who cannot log in to the system
c) call Shell command
cat /etc/passwd | awk -F : '/bash$/{print | "wc -l"}' /etc/passwd #Statistics of the number of users who can log in to the system