Under CentOS, the shell script enclosed in single quotes does not perform a workaround

Example one;

Touch test.sh

VI test.sh

Input

Test= ' echo ' test* "|grep [a-za-z0-9] |wc-c '

Echo $test

Save, Exit VI;

SH test.sh

Result: Echo "test*" |grep [a-za-z0-9] |wc-c

Description not implemented;

We modify a pair of single quotes to $ () and the result class is as follows:

Test=$ (echo "test*" |grep [a-za-z0-9] |wc-c)

Echo $test

Save, Exit VI;

SH test.sh

Results: 6

Instructions for successful execution!

This article is from the "one-day effort" blog, please be sure to keep this source http://java711.blog.51cto.com/1786533/1642028

Under CentOS, the shell script enclosed in single quotes does not perform a workaround