linux $() $difference

##linux $() $Difference

$

$ The symbol appears in different places, and the definition it represents will be different. For example, in bash, the $ symbol indicates that the current user is a normal user; in bash scripts. $ starts with a variable.

For example, here are some special variables:

$ represents the number of parameters

$0 is the name of the script itself

$1 is passed to the shell script The first parameter

$2 is the second parameter passed to the shell script

$@ represents all parameters, and all parameters are independent

$ is running The current process ID number of the script

that$ shows the exit status of the final command, 0 means there is no error, and other means there is an error.

$()

$(): The command is placed in parentheses, which has the same effect as `` backticks. Execute this command

For example, the function of $(command) is to execute the command and output the result (of course, this output is not on the screen, but must be placed in a specific context).

Recommended: "

Linux Tutorial"

The above is the detailed content of linux $() $difference. For more information, please follow other related articles on the PHP Chinese website!