Shell Tutorial String

1.Shell string

Strings are the most common and useful data types in shell programming (except numbers and strings, and no other type works well), strings can be in single quotes or double quotes, or without quotes.

1.1 Single quotation marks

Str= ' I am uniquefu '

Single-Quote String restrictions:

• Any character in a single quotation mark is output as is, and the variable in the single-quote string is not valid;
• A single quotation mark cannot appear in an apostrophe string (it does not work with an escape character for single quotes), but can be paired and used as a string concatenation

1.2 Double quotes

Name= "Http://www.cnblogs.com/uniquefu" str= "Hello, I know you is \" $name \ "! \ n "Echo ${str}

Output Result:

[Email protected] bin]#/test.sh Hello, I know you are "Http://www.cnblogs.com/uniquefu"! \ n

Advantages of double quotes:

• You can have variables in double quotes.
• Escape characters can appear in double quotes

1.3 Stitching strings

Your_name= "Uniquefu" # using double quotes greeting= "Hello," $your _name "!" greeting_1= "Hello, ${your_name}!" echo $greeting  $greeting _1# use single quotes to stitch greeting_2= ' Hello, ' $your _name '! ' greeting_3= ' Hello, ${your_name}! ' echo $greeting _2  $greeting _3

Run results

[Email protected] bin]#/test.sh Hello,  uniquefu! Hello, Uniquefu!hello, Uniquefu! Hello, ${your_name}!

1.4 Get string length

Your_name= "Uniquefu" Echo ${#your_name}

Output Result:

[Email protected] bin]#/test.sh  8

1.5 Extract substring

The following instance intercepts 5 characters from the first 3 characters of a string

Your_name= "Uniquefu" Echo ${your_name:2:5}

Output Result:

[Email protected] bin]#/test.sh  Iquef

1.6 Finding a string

Look for the position of the character I or f (which letter appears first to calculate which):

Your_name= "Uniquefu" echo ' expr index ' $your _name ' if '  # output 3

　Note: the above Script ' is an anti-quote, not a single quote ', do not look wrong oh 　

Shell Tutorial String