How to do what head, tail, more, less, sed do in Powershell? [closed]

Question

Get-Content (alias: gc) is your usual option for reading a text file. You can then filter further:

gc log.txt | select -first 10 # head
gc -TotalCount 10 log.txt     # also head
gc log.txt | select -last 10  # tail
gc -Tail 10 log.txt           # also tail (since PSv3), also much faster than above option
gc log.txt | more             # or less if you have it installed
gc log.txt | %{ $_ -replace '\d+', '($0)' }         # sed

This works well enough for small files, larger ones (more than a few MiB) are probably a bit slow.

The PowerShell Community Extensions include some cmdlets for specialised file stuff (e.g. Get-FileTail).

Here are the built-in ways to do head and tail. Don't use pipes because if you have a large file, it will be extremely slow. Using these built-in options will be extremely fast even for huge files.

gc log.txt -head 10 
gc log.txt -tail 10
gc log.txt -tail 10 -wait # equivalent to tail -f

more.exe exists on Windows, ports of less are easily found (and the PowerShell Community Extensions, PSCX, includes one).

PowerShell doesn't really provide any alternative to separate programs for either, but for structured data Out-Grid can be helpful.

Head and Tail can both be emulated with Select-Object using the -First and -Last parameters respectively.

Sed functions are all available but structured rather differently. The filtering options are available in Where-Object (or via Foreach-Object and some state for ranges). Other, transforming, operations can be done with Select-Object and Foreach-Object.

However as PowerShell passes (.NET) objects – with all their typed structure, eg. dates remain DateTime instances – rather than just strings, which each command needs to parse itself, much of sed and other such programs are redundant.

"-TotalCount" in this instance responds exactly like "-head". You have to use -TotalCount or -head to run the command like that. But -TotalCount is misleading - it does not work in ACTUALLY giving you ANY counts...

gc -TotalCount 25 C:\scripts\logs\robocopy_report.txt

The above script, tested in PS 5.1 is the SAME response as below...

gc -head 25 C:\scripts\logs\robocopy_report.txt

So then just use '-head 25" already!

If you need to query large (or small) log files on Windows, the best tool I have found is Microsoft's free Log Parser 2.2. You can call it from PowerShell if you want and it will do all the heavy lifting for you, and very fast too.