The method of string interception under shell

One of the first few instances of the Linux shell intercepting strings, the first 8 bits are intercepted:

The method is as follows: A=1234STERRERWRWRETW below

1.expr substr "$a" 1 8

           

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2.echo $a |cut-c1-8

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3..echo $a |dd Bs=1 count=8

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Two. Intercept by the specified string

1, the first method:

1> ${val##*string} (double #* intercept)

A string after the last string is truncated from left to right

Example: A= 123stringrwtw134string456

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2>${varible#*string} (single #* intercept)

from left to right a string after the first string is intercepted

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3> ${val%%string*} ( double%* intercept )

To intercept the string before the last string from right to left

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4> ${val%string*} intercepts the string before the first string from right to left (single%* intercept)

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2. The second method:

1>${val:n1:n2}: Intercept variable val from left N1 begins intercepting N2 strings. Note: string from 0 count

Continue to use the A variable above

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2>${VAL:0-N1:N2}: Intercepts the variable Val from the right start 0 to N1 between the string intercept n2. (from left to right when intercepting)

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3>${VAL:0-N1}: Intercept variable val n1 A string from right start

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4>${VAL:N1} intercepts all strings after N1 start

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This article is from the "Output Diamond pattern" blog, so be sure to keep this source http://10541571.blog.51cto.com/10531571/1790377

The method of string interception under shell