Method for getting substrings in Shell

Method 1 for getting substrings in Shell simple common method $ exprsubstr & quot; linuxsong & quot; 15linux2 direct variable truncation $ a & quot; linuxsong & quot; $ echo $ {: 0: 5} use cut to intercept the string $ echo & quot; linuxsong & quot; | method 1 to obtain the substring in c Shell. common method $ expr substr "linuxsong" 1 5 linux 2. intercept $ a = "linuxsong" $ echo $ {a: 0: 5} linux 3. use cut to intercept the string $ echo "linuxsong" | cut-c 1-5 # use the 1-5 characters linux 4. awk substring $ echo "linuxsong" | awk '{print substr ($, 5)} 'Linux 5. head substring $ echo "linuxsong" | head-c5linux 6. tail method 7. echo "hello" | tr' [a-z] ''[A-Z]'' for case-insensitive sed method conversion