Friday Fun Re-Run Last Command

Ok, I'll be the first to admit you might not find a production use for this tip, but that's what makes it fun. Interactively, you can always hit the up arrow to get the last command in your command buffer. But what if you are running a script and for some reason want to re-rerun the last command? Using Get-History we can get a listing of all the commands. This cmdlet has an alias of 'h'. To re-run any command we use Invoke-History and specify the id number. Invoke-History has an alias of 'r'.

[cc lang="PowerShell"]

PS S:\> r 163
get-service spooler

Status Name DisplayName
------ ---- -----------
Running spooler Print Spooler
[/cc]

For the programmatic approach, we need to find the last id number in history. Here's how:

[cc lang="PowerShell"]
PS S:\> (get-history)[-1].id
167
[/cc]

The Get-History expression returns an array. Using [-1] returns the last item in the array and then I'm only asking for the ID property. See where this is going? To run the last command we can pass this value to Invoke-History. We could do this, because the ID parameter accepts pipeline binding by property name:

[cc lang="PowerShell"]
(get-history)[-1] | invoke-history
[/cc]

Or like this (using aliases to shorten the command for an interactive session):

[cc lang="PowerShell"]
r (h)[-1]
[/cc]

Finally, we might want to turn this into a quicky function:

[cc lang="PowerShell"]
function rlast {
Invoke-History (Get-History)[-1]
}
[/cc]

Not life-changing, I know. But perhaps you'll pick up a tidbit or two about how PowerShell works.

---

---