Curly braces allow you to specify a set of characters from which the shell automatically forms all possible combinations. To make this work, the characters to be combined with the given string must be specified as a comma-separated list with no spaces:
$ touch file{1,2,3} $ ls
$ mkdir directory{1,2,3}{a,b,c} $ ls
$ touch file{a..z} $ ls
The following is the summary of various I/O-redirection and logical operators:
For example: ...