Powershell Commands useful for large CSV files

1) To get the header line, ie: first row in a CSV file 

gc .\FILENAME.csv -TotalCount 1

2) To get the header line, and export it to another CSV file.  Note the use of Set-Content rather than Export-CSV

gc .\FILENAME.csv -TotalCount 1 | Set-Content .\header-file-name.csv

3) To filter the CSV file based on a regex search , and export the matches to another file.

gc .\FILENAME.csv | Select-String -Pattern ( '.*2018-11-20.*' ) | Set-Content .\inner-file-name.csv

4) To see the last few lines, like tail 

gc .\20181206_InteractionDetails.csv | select -last 10