Shell script - sort, uniq, TR, array sort, cut, Eval command configuration

shell Script ——sort、uniq、tr、 Array sorting 、cut、eval Command configuration

One 、sort command

Sort the contents of the file in behavioral units , It can also be sorted according to different data types

1、 Grammar format

sort [ Options ] Parameters
cat file | sort Options

2、 Common options

3、 Command configuration and examples

sort -n testfile2
sort -t ‘:’ -k 3 -n /etc/passwd
du -a | sort -nr -0 du.txt

[ Failed to transfer the external chain picture , The origin station may have anti-theft chain mechanism , It is suggested to save the pictures and upload them directly (img-mHomdKBa-1658074073763)(https://s2.loli.net/2022/07/18/EkQ92HS3egGvjbW.png)]

Two 、uniq command

Used to report or ignore consecutive duplicate lines in the file , Often with sort Command in combination with

1、 Grammar format

uniq [ Options ] Parameters
cat file | uniq Options

2、 Common options

3、 Command configuration and examples

uniq testfile3
sort -n testfile3 | uniq -c

3、 ... and 、tr command

Commonly used to replace characters from standard input 、 Compress and delete

1、 Grammar format

tr [ Options ] [ Parameters ]

2、 Common options

3、 Parameters

Character set 1

Specifies the original character set to convert or delete . When performing a transformation operation , Parameters must be used “ Character set 2” Specifies the target character set of the transformation . But when you delete , No parameters required “ Character set 2”;

Character set 2

Specifies the target character set to convert to

4、 Command configuration and examples

echo “abc” | tr ‘a-z’ ‘A-Z’

echo -e “abc\ncabcdab” | tr -c “ab\n” “0”
echo -e “abc\ncabcdab” | tr -c “ab” “0”

echo ‘hello world’ | tr -d ‘od’
echo “thissss is a text linnnnnnne.” | tr -s ‘sn’

Delete blank lines
echo -e “aa\n\n\n\n\nbb” | tr -s “\n”
cat testfile5 | tr -s “\n”

Put the colon in the path variable ":“, Replace with a newline ”\n"
echo $PATH | tr -s “:” “\n”
echo -e “aa\n\n\n\n\nbb” | tr -s "\n” “:”

Delete Windows file “ cause ” Of "^M’ character :
cat abc.txt | tr -s “\r” “\n” > new_ file
or
cat abc.txt | tr -d “\r” > new_file
Linux Line break encountered in (“\n”) Will enter + Line feed operation , Instead, the carriage return character will only be used as a control character (“^M”) Show , No carriage return occurs . and windows in Want a carriage return
+ A newline (“\r\n”) Will enter + Line break , Missing a control character or out of order cannot start another line correctly .

cat -v abc.txt
dos2unix abc.txt

Four 、 Array sorting

echo ${array[*]} | tr ’ ’ ‘\n’ | sort -n > file

a=0
for i in $(catfile)doarray[$a]=KaTeX parse error: Expected 'EOF', got '#' at position 11: i let a++ #̲array+=(i)
done

5、 ... and 、cut command

Display the specified part in the row , Delete the specified field in the file

1、 Grammar format

cut Options Parameters
cat file | cut Options

2、 Common options

3、 Command configuration and examples

cut -d ‘:’ -f 1 /etc/passwd
grep ‘/bin/bash’ /etc/passwd|cut -d ‘:’ -f 1-4,6,7
# With - Separated start and end fields specify the range of fields
grep ‘/bin/bash’ /etc/passwd|cut -d ‘:’ --complement -f 2
# Exclude the second field
cut -d ‘:’ -f1,7 --output-delimiter=’ ’ /etc/passwd
# The output separator is separated by spaces

i=123456789
echo $i| cut -b 1-3 # Starting from 1 Start
123

echo ${i:0:3} # Starting from 0 Start
expr substr $i 1 3 # Starting from 1 Start

6、 ... and 、eval command

with eval when ,shell Will scan it twice before executing the command .eval The command will first scan the command line for all permutations , Then execute the command . This command is applicable to those variables that cannot perform their functions in one scan . This command scans variables twice

、eval command

with eval when ,shell Will scan it twice before executing the command .eval The command will first scan the command line for all permutations , Then execute the command . This command is applicable to those variables that cannot perform their functions in one scan . This command scans variables twice

[ Outside the chain picture transfer in …(img-oOSVIXFn-1658074073766)]