A detailed approach to shell string interception _linux Shell

The first 8 bits of a character variable are intercepted by the Linux shell, with the following methods:

Copy Code code as follows:

1.expr substr "$a" 1 8
2.echo $a |awk ' {print substr (, 1,8)} '
3.echo $a |cut-c1-8
4.echo $
5.expr $a: ' (. \). * '
6.echo $a |dd Bs=1 count=8 2>/dev/null

Second, intercept by the specified string
1, the first method:
${varible##*string} to intercept the string after the last string from left to right
${varible#*string} to intercept the string after the first string from left to right
${varible%%string*} to intercept the string after the last string from right to left
${varible%string*} to intercept the string after the first string from right to left
"*" is just a wildcard character that you can not

Example:

Copy Code code as follows:

$ myvar=foodforthought.jpg
$ echo ${myvar##*fo}
Rthought.jpg
$ echo ${myvar#*fo}
Odforthought.jpg

2, the second method: ${varible:n1:n2}: Intercept the variable varible from N1 to N2 between the string.

You can select a specific substring by using a variable extension of another form, depending on the specific character offset and length. Try entering the following line in bash:

Copy Code code as follows:

$ exclaim=cowabunga
$ echo ${exclaim:0:3}
Cow
$ echo ${exclaim:3:7}
Abunga

This form of string truncation is simple, with a colon separated to specify the starting character and substring length.

Divided according to the specified requirements:
Like getting the suffix name

Copy Code code as follows:

Ls-al | Cut-d "."-f2

Application Experience:

Copy Code code as follows:

$MYVAR = "12|DADG"
Echo ${myvar##*|} #打印分隔符后的字符串
Dafa
Echo ${myvar%%|*} #打印分隔符前的字符串
12