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 = objectcat 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)