Shulou(Shulou.com)06/01 Report--

1.# intercept, delete the left character and retain the right character.

Code: echo ${var#*//}

Where var is the variable name, # is the operator, and * / / means to delete the first / / and all characters on the left from the left.

Example:

Results:

2. Intercept the characters on the left and keep the characters on the right

Code: echo ${var##*/}

Where # * / means to delete the last (rightmost) / sign and all characters on the left from the left

Example:

Results:

3.% intercept, delete the right character and keep the left character

Code: echo ${var%/*}

Where% / * means to start on the right and delete the first / sign and the characters on the right

Example:

Results:

4%% intercept, delete the right character and keep the left character

Code: echo ${% / *}

Where% / * means to start from the right and delete the last (leftmost) / and right character

Example:

Results:

5. Start with the number of characters on the left and the number of characters

Code: echo ${var:0:5}

Where 0 indicates the beginning of the first character on the left, and 5 represents the total number of characters

Example:

Results:

6. Start with the character on the left and go to the end

Code: echo ${var:7}

The seven of them starts with the eighth character on the left and ends.

Example:

Results:

7. Start with the number of characters on the right and the number of characters

Code: echo ${var:0-7:3}

Where 0-7 indicates the seventh character from the right, and 3 indicates the number of characters.

Example:

Results:

8. Start with the character on the right and go to the end

Code: echo ${var:0-7}

It starts with the seventh character on the right and ends.

Example:

Results:

The 9.cut command mainly accepts three positioning methods:

(1) Bytes, with option-b

(2) characters, with the option-c

(3) Domain, use the option-f

Example:

From this point of view, there seems to be no difference between-b and-c options, but it is not, because who outputs single-byte characters, so there is no difference between-b and-c. If changed to Chinese, only-c can be used, and-b output is garbled.

The-b and-c we mentioned can only extract information from fixed-format documents, but they are not useful for non-fixed-format information, so "fields" are used.

Example:

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