Linux ${} Character-channeling method summary

A summary of how Linux character channeling is intercepted

1. Summary of Commands

• ${target-string#*sub-string}

• ${target-string##*sub-string}

• ${target-string%sub-string*}

• ${target-string%%*sub-string*}

----------------------------------------------------------------------------

• ${target-string:start-index:string-numbers}

• ${target-string:start-index}

• ${target-string:0-start_index:string-numbers}

• ${target-string:0-start_index}

2. Summary of examples

st1= ' Http://www.baidu.com/image/image.png '

• From the left side of the st1, cut off the left part of the position where the character first appears, leaving the right part intact and not containing '/'.

# echo ${st1#*/}/www.baidu.com/image/image.png

• From the left side of the st1, cut off the left part of the last occurrence of this character, leaving the right part and not containing the '/'.

# echo ${st1##*/}image.png

----------------------------------------------------------------------------

st1= ' Http://www.baidu.com/image/image.png '

• From the right side of the st1, cut off the right part of the first occurrence of the character, leaving the left part intact and not containing the '/'.
  

# echo ${st1%/*}http://www.baidu.com/image

• From the right side of the st1, cut off the right part of the last occurrence of this character, leaving the left part intact and not containing '/'.
  

# echo ${st1%%/*}http:

-----------------------------------------------------------------------------

st1= ' Http://www.baidu.com/image/image.png '

• From the left side of St1, start with the first character {0} and intercept {4}4 characters.

# echo ${st1:0:4}http

• From the left side of the ST1, cut down 7 characters and keep the right part

# echo ${st1:7}www.baidu.com/image/image.png

---------------------------------------------------------------------------------------

st1= ' Http://www.baidu.com/image/image.png '

• Start with the 10th character {0-10} on the right side of St1 and intercept 6 characters.

# echo ${st1:0-10:6}/image #不是ge. png because it is a 10th character from the right of the first, that is, 6 characters from the '/'.

• Start with the 10th character {0-10} on the right side of ST1 and intercept all the characters on the right.

# echo ${st1:0-10}/image.png

3. Memory methods

• Be sure to divide the intercept, or cut off.

• There are 5 symbols, ' # ' # # '% ' of percent '    

#

This article is from the "Frog Technology Archive" blog, so be sure to keep this source http://frogtwo.blog.51cto.com/3805708/1939143

Linux ${} Character-channeling method summary