
histexpand:tldr:2b239
histexpand: Run the Nth command of the history.
$ !${n}
try on your machine
The command "!${n}" is a way to refer to the value of a specific argument passed to a shell script or function. Here's how it works: 1. The "$n" syntax is used to access the value of the nth argument.
- For example, "$1" refers to the first argument, "$2" refers to the second argument, and so on. 2. The "!" symbol is used in combination with the "$n" syntax to expand the argument's value.
- This is known as history expansion or event designators in shells like bash. By using "!${n}", you can access and manipulate the value of an argument in various ways. For example, you can use it in a command to recall and execute a previous command with the nth argument as part of it. Here's an example to further illustrate: Let's say you have a shell script named "mycommand.sh" and you run it with two arguments: $ ./mycommand.sh argument1 argument2 Inside the script, if you want to access the value of the first argument, you can use: echo "$1" Similarly, if you want to use the value of the second argument in a command, you can use: !${2} This will expand to the value of the second argument. So, if the second argument is "argument2", the command "!${2}" will be equivalent to "argument2" and will have the same effect as directly using "argument2" in your script.
This explanation was created by an AI. In most cases those are correct. But please always be careful and
never run a command you are not sure if it is safe.