Linux Learning (22) Shell Basics (iii) Special symbols, sort, WC, uniq, tee, TR, split

First, special symbols

*: any of any characters

 
[[email protected] ~]# ls 1*
1bak.zip  1.tar  1.zip.bz2

1:
1.txt  2
[[email protected] ~]# ls 1*2

？ : An arbitrary character

 
[[email protected] ~]# ls 2?tar
2.tar

#: Notes

[[email protected] ~]# #ls
[[email protected] ~]# 

\: de-intention

[[email protected] ~]# a=3
[[email protected] ~]# echo $a
3
[[email protected] ~]# echo \$a
$a
[[email protected] ~]# echo "\$a"
$a

|: Pipe Symbol

The function of a pipe symbol is to put the output of the previous command as the standard input for the next command:

[[email protected] ~]# ls|wc -l
21

Second, sort

The sort command is used to sort the.

The default is sorted by the first letter of the ASCII code:

[[email protected] ~]# ls|sort
1
1bak.zip
1.tar
1.zip.bz2
2
2.tar
3
33.tar
3.tar.gz
3.zip
4.tar
4.tar.bip2
4.zip
5
5.zip
6
7.txt
8.txt
999.txt
9.txt
[[email protected] ~]# cat 3.txt | sort

[
$
$
%^
3
33
55
6
6
666
dfd
dfdf
e
gr
kQ$
Q$
Q$
t

Sort by Number:

[[email protected] ~]# sort -n 3.txt

[
$
$
%^
dfd
dfdf
e
gr
kQ$
Q$
Q$
t
3
6
6
33
55
666

The experiment found that when sorting by numbers, both letters and special characters were treated as 0.

Reverse

 
[[email protected] ~]# sort -r 3.txt
t
Q$
Q$
kQ$
gr
e
dfdf
dfd
666
6
6
55
33
3
%^
$
$
[

Sort by Segment:

 
[[email protected] ~]# sort -t: -nrk3 666.txt
ruanwenwu:x:1000:1000::/home/ruanwenwu:/bin/bash
systemd-bus-proxy:x:999:997:systemd Bus Proxy:/:/sbin/nologin
systemd-network:x:192:192:systemd Network Management:/:/sbin/nologin
nobody:x:99:99:Nobody:/:/sbin/nologin

Third, cut

The Cut command is used for cutting. -d Specifies the delimiter,-f Specifies the number of segments, and-c specifies several characters

[[email protected] ~] # cut -d: -f 3,4 666.txt
0: 0
1: 1
2: 2
3: 4
4: 7
5: 0
6: 0
7: 0
8:12
11: 0
12: 100
14:50
99:99
999: 997
192: 192
81:81
59: 996
59:59
89:89
74:74
1000: 1000
[[email protected] ~] # cut -d: -f 3,4 -c1 666.txt
cut: can only specify one type in the list
Try ‘cut --help’ for more information.

The experiment shows that it is not possible to cut both segments and characters.

Intercept characters:

 
[[email protected] ~]# cut -c 2-4 666.txt
oot
in:
aem
dm:
p:x
ync

Four, WC

The WC command is used to count the number of rows (most commonly used), the number of words and the word count.

Wc-l count rows.

Wc-w count the number of words.

Wc-m or wc-c counts the number of letters. These two commands will count the hidden letters.

[[email protected] ~]# vim 777.txt
[[email protected] ~]# wc -c 777.txt 
19 777.txt
[[email protected] ~]# cat 777.txt 
df dd
cc
dd dd dd

[[email protected] ~]# cat -A 777.txt 
df dd$
cc$
dd dd dd$
$
[[email protected] ~]# wc -m 777.txt 
19 777.txt
[[email protected] ~]# wc -w 777.txt 
6 777.txt

Wu, Uniq

The Uniq command is often used in conjunction with the sort command. Because if two identical rows are not together, they cannot be uniq.

 
[[email protected] ~]# uniq 1.txt
3
4
3
5
6
7
87
8

Let's sort it out and uniq it:

 
[[email protected] ~]# sort 1.txt|uniq
3
4
5
6
7
8
87

Uniq-c shows the number of repetitions per line:

 
[[email protected] ~]# sort 1.txt|uniq -c
      2 3
      1 4
      1 5
      1 6
      1 7
      1 8
      1 87
六、tee

Six, Tee

The tee command takes the standard input, redirects it, and prints the standard input.

 
[[email protected] ~]# cat 1.txt|tee 3.txt
dffdf
[[email protected] ~]# cat 1.txt|tee -a 3.txt
dffdf
[[email protected] ~]# cat 1.txt|tee -a 3.txt
dffdf
[[email protected] ~]# cat 1.txt|tee -a 3.txt
dffdf
[[email protected] ~]# cat 3.txt
dffdf
dffdf
dffdf
dffdf

Seven, tr

The purpose of the TR command is to replace the standard input.

[[email protected] ~] # tr ‘a-z’ ‘A-Z’ ‘sdfsdfsgdgfs’
tr: extra operand "sdfsdfsgdgfs"
Try ‘tr --help’ for more information.
[[email protected] ~] # tr ‘a-z’ ‘A-Z’
dfdfdfdfdfdfd
DFDFDFDFDFDFD

Eight, split

Split is a cut file. Split can be cut by row (split-l), or by size (split-b).

First, let's prepare a large file. Merges all the conf files in the system into the a.txt.

" *.conf " -exec Cat {} >> a.txt \;

Cut by line:

[[email protected] ~] # du -sh a.txt
544K a.txt
[[email protected] ~] # wc -l a.txt
21746 a.txt
[[email protected] ~] # mkdir / tmp / test2
[[email protected] ~] # mv a.txt / tmp / test2 /
[[email protected] ~] # cd! $
cd / tmp / test2 /
[[email protected] test2] # ls
a.txt
[[email protected] test2] # ls -l
Total usage 544
-rw-r--r--. 1 root root 554540 November 18 12:37 a.txt
[[email protected] test2] # wc -l a.txt
21746 a.txt
[[email protected] test2] # wc -l 10000 a.txt
wc: 10000: no such file or directory
  21746 a.txt
  21746 Total dosage
[[email protected] test2] # ls
a.txt
[[email protected] test2] # split -l 10000 a.txt
[[email protected] test2] # ls
a.txt xaa xab xac

Cut by Size:

[[email protected] test2]# !find
find / -type f -name "*.conf" -exec cat {} >> a.txt \;
[[email protected] test2]# ls
a.txt
[[email protected] test2]# split -b 100k a.txt
[[email protected] test2]# ls
a.txt  xaa  xab  xac  xad  xae  xaf

Specify the split file prefix:

[[email protected] test2]# split -b 100k a.txt abc.
[[email protected] test2]# ls
abc.aa  abc.ab  abc.ac  abc.ad  abc.ae  abc.af  a.txt

Nine, special symbols

Note: | | Yes, if the previous command was executed, the following will not be executed.

[[email protected] test2]# [ -d ruanwenwu ] || mkdir ruanwenwu
[[email protected] test2]# ls
abc.aa  abc.ab  abc.ac  abc.ad  abc.ae  abc.af  a.txt  ruanwenwu

Linux Learning (22) Shell Basics (iii) Special symbols, sort, WC, uniq, tee, TR, split