The '<' operator is reserved for future use

Question

I am using PowerShell and am trying to run the following command:

.\test_cfdp.exe < test.full | tee test.log

test.full is a script that mimics command line inputs to test_cfdp.exe. However, I get the following error:

The '<' operator is reserved for future use.

Is there another way (i.e. cmdlet) I can use to get this command to work in PowerShell?

Ruben Bartelink · Accepted Answer · 2016-03-17T21:22:05.037

95

This was not supported in PowerShell v1 [and as of v5, it's still not...]

An example workaround is:

Get-Content test.full | .\test_cfdp.exe | tee test.log

edited Mar 17 '16 at 21:22

answered Jan 27 '10 at 17:04

Ruben Bartelink

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You can use the alias `cat` to get file content easier. – iTzVoko Jun 01 '23 at 13:51
@aliayed Yes, or `gc` or `type`; however, it's common convention in forums etc to use the canonical cmdlet name explicitly, as anyone that knows the alias will cope, but the cmdlet name is far more searchable (if someone has a good link for an article that explains this, happy to edit it into this comment) – Ruben Bartelink Jun 01 '23 at 15:01

score 63 · Answer 2 · answered May 14 '13 at 16:52

63

Also try:

cmd /c '.\test_cfdp.exe < test.full | tee test.log'

answered May 14 '13 at 16:52

earGrowth

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`tee` is an alias for PowerShell's `Tee-Object` cmdlet, though, so this won't work the same/at all. – Lance U. Matthews Sep 20 '22 at 01:13
this doesn't work at all, unless there's a real `tee.exe` or `tee.bat`... in `%PATH%`, because `tee` isn't available in cmd. It only works in PowerShell by default where `tee` is an alias – phuclv Nov 05 '22 at 11:39
yes - running the command in Command Prompt works fine. This error is misleading. – kiev Apr 14 '23 at 16:13

score 6 · Answer 3 · answered Dec 03 '21 at 10:53

In version 7 of PowerShell, you still need to use Get-Content to get the contents of an item in the specified location. For example, if you want to load a file into a Python script and write the result to a file. Use this construct:

PS > Get-Content input.txt | python .\skript.py > output.txt

Or with displayed and saved in a file:

PS > Get-Content input.txt | python .\skript.py | tee output.txt

Or switch to cmd to use the '<' operator:

C:\>python .\skript.py < input.txt > output.txt

Switching to `cmd` and using the `<` operator was the easiest solution in my case, thanks! — Laurin Herbsthofer, Aug 10 '23 at 09:54

score 2 · Answer 4 · answered Jun 29 '22 at 11:21

2

In case PowerShell is not mandatory , running the command in Command Prompt works fine.

answered Jun 29 '22 at 11:21

Umesh Khatiwada

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Your answer could be improved with additional supporting information. Please [edit] to add further details, such as citations or documentation, so that others can confirm that your answer is correct. You can find more information on how to write good answers [in the help center](/help/how-to-answer). – Community Jul 01 '22 at 14:36
That has already been proposed in [this earlier and much-upvoted answer](https://stackoverflow.com/a/16548699/150605). – Lance U. Matthews Sep 20 '22 at 01:14

score 2 · Answer 5 · answered Sep 29 '22 at 11:20

Because I dev on windows and deploy on linux I have created this powershell function. The solutions above where not appropriate because the binary file I had to restore. The knowledge of the bash-script is borrowed from: How to invoke bash, run commands inside the new shell, and then give control back to user?

$globalOS = "linux" #windows #linux

function ExecuteCommand($command) {
    if($command -like '*<*') {
        #Workaround for < in Powershell. That is reserved 'for future use'
        if ($globalOS -eq "windows") {
            & cmd.exe /c $command
        } else {
            $wrappercommand = "''" + $command + " ; bash''"
            & bash -c $wrappercommand
        }
    } else {
        Invoke-Expression $command
    }
}

$command = "docker exec -i mydockerdb pg_restore -U postgres -v -d mydatabase < download.dump"
ExecuteCommand($command)

score 1 · Answer 6 · answered Jun 08 '13 at 09:20

1

If you want to run this command more times, you can just make a *.bat file with the original syntax. That's another solution.

answered Jun 08 '13 at 09:20

seniorpreacher

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Dont use powershell, you can use cmd prompt. In windows go to respective folder and type cmd in address bar to open the cmd prompt and there < signs can be used. – Braham Dev Yadav Aug 22 '23 at 18:14

The '<' operator is reserved for future use

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