Powershell: Feature Request: Add -Line parameter to Get-Content

[juneb]

Scenario: I want only line 1053 from a large file. This might be a line flagged by a debugger, malware detector, or script analyzer.

There are many ways to do this, but some are very inefficient. It would be great to enclose a best-performance method in a parameter.

Get-Content -Line (scalar)
When the line doesn't exist in the file, Get-Content returns nothing (no error).

[pcgeek86]

Good idea. What if you wanted to obtain a range of lines, or an array of individual lines?

### Get an individual line
Get-Content -Path ... -Line 1053

### Get a range of lines
Get-Content -Path ... -Line 1053-1058

### Get more than one individual line
Get-Content -Path ... -Line 1053,2130

### Get line ranges and individual lines
Get-Content -Path ... -Line 1053-1058, 2130

I suppose you could treat a single line as a range with a length of one.

[rkeithhill]

Nice add @pcgeek86 but remember the range operator is .. so Line would be of type [int[]] and take -Line 1053, -Line 1053..1058 and -Line (1053..1058),2130.

[iSazonov]

When the line doesn't exist in the file, Get-Content returns nothing (no error).

I believe this should cause an exception. If we do not want it, then -ErrorAction SilentlyContinue

[rkeithhill]

Well, at the most I would say a missing line would cause a non-terminating error.

[rkeithhill]

An issue to think about is whether -Line specifies 0 or 1 based indices. I think 1-based is the way to go since most tools report line errors/warnings using 1-based indices.

[iSazonov]

Error reporting is not the only scenario and perhaps it is better to use a general rule - start with 0.

[BrucePay]

Hmm "Get-Content -Path ... -Line 1053" instead of (Get-Content -Path ...)[1053] doesn't seem like much of a win to me (maybe for very large files...). Also remember that Get-Content is a provider cmdlet so is -Line a dynamic parameter for the file system provider? Or does it apply to all providers. Finally (ignoring pipeline performance issues)
get-content -path ... | select -range 1053,1055
is more "powershelly".

[BrucePay]

Also note that you can also do
Get-Content -Path ... | Select -Skip 1052 -First 1

[powercode]

Most likely a dynamic param on FileSystemProvider. @BrucePay: I agree that your examples are more powershelly, but it is also nice to have scripts that doesn't only work on small files (where work may be "work reasonably fast").
(Get-Content -Path ...)[1053] may be really bad.

I don't have a strong opinion about how to solve this, but in general, I would like to see a bit more focus on making our core cmdlets performant even on very large data sets.

I find myself starting with pipelines for interactively trying things out, but quite often moving to other solutions when making a module out of my findings, often for performance reasons. And as with most perf opt, the result is less readable.

[iSazonov]

If this can be done internally, this should be done internally for performance reasons.