Command Substitution
Command substitution uses the output of a command as an expansion
Example:
echo $(ls)
file $(ls -d /usr/bin/* | grep zip)
You can also use quotes for command substitution
Example:
ls -l ' which cp'
Bash Pathname Expansion in Linux
When you type a command and press enter, bash performs several processes upon the text before carrying out our command as a command. The process that makes this happen is called expansion. For example, suppose you use the echo command for standard output.
echo hi Output hi
If you use echo with asterisk wildcard echo will print your directory. Suppose you have two files in the current working directory. The first file name is file1.txt and file2.txt then you will use echo with asterisk wildcard then It will print your directory name.
Example:
Types of Expansion
- Pathname Expansion
- Tilde Expansion
- Arithmetic Expansion
- Brace Expansion
- Parameter Expansion
- Command Substitution