Shellscript: String operations

Truncate string

$ Echo 'expr substr 123 2 1'

Truncate from 0 to 3

$ Echo $ {path: 0: 3}

Replace spaces-

$ Echo "a B" | TR """-"

Var1 = "hello"

Var2 = "he"

String inclusion

Method 1-> intercept a string

Echo $ {var1: 0: 2} # extract 2 bits starting from 0->$ {Variable: 0: n}

If [$ {var1: 0: 2 }=$ var2]; then

Echo "1: Include"

Fi

Method 2

-Eq-> two equal values (equal)

$? -> Check the execution result of the last command. The value 0 indicates normal, and the value 0 indicates abnormal. [The default value is 1].

Grep "keywords" File

-> If keywords are available, the output result code is 0.

-> NO keywords does not output content, but the result code is 1 [Echo $?]

-> Grep "keywords" file-Q [-Q-> quiet; Do not write anything to standard output. exit immediately with zero status if any match is found, even if an error was detected.]

Echo "$ var1" | grep-Q "$ var2"

If [$? -EQ 0]; then

Echo "2: Include"

Fi

# Method 3

Echo "$ var1" | grep-Q "$ var2" & Echo "include" | echo "not"

# Method 4

[["$ {Var1/$ var2 /}"! = "$ Var2"] & Echo "include" | echo "not"

This article is from the "andyhdchoice" blog, please be sure to keep this source http://andyhdchoice.blog.51cto.com/1521623/1548777

Shellscript: String operations