Note: PowerShell is object based, as opposed to byte stream based Unix utilities. This means text operations aren't that common, and also means many idioms aren't directly translateable.
var=text
->$var = object
cat file1 file2 file3 > target
->gc -Encoding Byte file1,file2,file3 | sc -Encoding Byte target
(binary concatenation, with text files you can specify different encoding or let it guess)curl
->iwr
(Invoke-WebRequest
)date
->date
(Get-Date
)man command-name
->help command-name
(Get-Help
)