linux[Base]-10-command-line wildcard [01]

command-line wildcard characters

command-line wildcard characters:

An example:

[Email protected] ~]# LS/DEV/SDA

/dev/sda

[Email protected] ~]# ls/dev/sda1

/dev/sda1

[email protected] ~]# ls/dev/sda2

　　　　　　　　/dev/sda2

[Email protected] ~]# Ls/dev/sda3

Ls:cannot access/dev/sda3:no such file or directory

The role of wildcards here is you're not sure how many partitions, partition numbers, he can help you determine

* Match 0 or more characters

? Match any single character

[0-9] numbers within the matched range

[ABC] matches the given character

Instance:

[Email protected] ~]# ls/dev/sda*

/dev/sda/dev/sda1/dev/sda2

[Email protected] ~]# LS/DEV/SDA?

/dev/sda1/dev/sda2

[[email protected] ~]# ls/dev/sda[0-9]

/dev/sda1/dev/sda2

[[email protected] ~]# LS/DEV/SD[ABC]

/dev/sda

[Email protected] ~]# LS/DEV/SD[ABC]?

　　　　　　　　/dev/sda1/dev/sda2

[Email protected] ~]# ls/dev/sd[abc]*

　　　　　　　　/dev/sda/dev/sda1/dev/sda2

In addition Bash supports many special character extensions:

\ (backslash) escapes a single character later

"(single quote) to escape all characters

"" (double quote) variable is still in effect

"(anti-quote) EXECUTE command statement

Variable takes effect:

[Email protected] ~]# price=5

[Email protected] ~]# echo "Price is $Price"

Price is 5

But if you want to show the price as $ $, and it conflicts with the variable, it's time to use the escape character \ Backslash

[[email protected] ~]# echo "Price is $ $Price"

Price is 6892Price

[Email protected] ~]# echo "Price is \$ $Price"

Price is $

Use single quotation marks to escape all characters

[Email protected] ~]# echo ' Price is \$ $Price '

Price is \$ $Price

Use "to execute command statements

[[email protected] ~]# echo ' uname-a '

Linux msl23-linux.com 3.10.0-123.el7.x86_64 #1

SMP Mon May 5 11:16:57 EDT x86_64 x86_64 x86_64 gnu/linux

[[email protected] ~]# echo ' uname-r '

3.10.0-123.el7.x86_64

linux[Base]-10-command-line wildcard [01]