"Unknown Switch" error when using 7-zip in PowerShell script to archive file names that start with a `-`

Question

I have a series of files in a folder that contain large log files

-20180907 1229 debug.log
-20180907 1229 system.log

I want to write a PowerShell script to archive them down in size. Here's my script:

dir *.log | % {
    $archive = '"' + $_.Name + '.7z"'
    $archive
    $source = '"' + $_.Name + '"'
    $source
    &"C:\Program Files\7-Zip\7z.exe" -mx9 a -t7z $archive $source -WhatIf
}

When I run it, however, I get the following output:

"-20180907 1229 debug.log.7z"
"-20180907 1229 debug.log"
7z.exe : 
At C:\Users\User\Temporary\Test 7z\archive-logs.ps1:6 char:5
+     &"C:\Program Files\7-Zip\7z.exe" -mx9 a -t7z $archive $source
+     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : NotSpecified: (:String) [], RemoteException
    + FullyQualifiedErrorId : NativeCommandError

Command Line Error:
Unknown switch:
-20180907 1229 debug.log.7z
"-20180907 1229 system.log.7z"
"-20180907 1229 system.log"
7z.exe : 
At C:\Users\User\Temporary\Test 7z\archive-logs.ps1:6 char:5
+     &"C:\Program Files\7-Zip\7z.exe" -mx9 a -t7z $archive $source
+     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : NotSpecified: (:String) [], RemoteException
    + FullyQualifiedErrorId : NativeCommandError

Command Line Error:
Unknown switch:
-20180907 1229 system.log.7z

Even though I am wrapping the file name in double quotes it appears as 7-Zip is ignoring the double quotes.

Any ideas?

I tried this variant (wrapping the file names in single quotes):

dir *.log | % {
    $archive = "'" + $_.Name + ".7z'"
    $archive
    $source = "'" + $_.Name + "'"
    $source
    &"C:\Program Files\7-Zip\7z.exe" -mx9 a -t7z $archive $source
}

And this time I got this output:

'-20180907 1229 debug.log.7z'
'-20180907 1229 debug.log'

7-Zip 18.05 (x64) : Copyright (c) 1999-2018 Igor Pavlov : 2018-04-30

Open archive: '-20180907 1229 debug.log.7z'
--
Path = '-20180907 1229 debug.log.7z'
Type = 7z
Physical Size = 32
Headers Size = 0
Solid = -
Blocks = 0

Scanning the drive:
7z.exe : 
At C:\Users\User\Temporary\Test 7z\archive-logs-B.ps1:6 char:5
+     &"C:\Program Files\7-Zip\7z.exe" -mx9 a -t7z $archive $source
+     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : NotSpecified: (:String) [], RemoteException
    + FullyQualifiedErrorId : NativeCommandError

WARNING: The system cannot find the file specified.
'-20180907 1229 debug.log'
0 files, 0 bytes

Updating archive: '-20180907 1229 debug.log.7z'

Add new data to archive: 0 files, 0 bytes


Files read from disk: 0
Archive size: 32 bytes (1 KiB)

Scan WARNINGS for files and folders:

'-20180907 1229 debug.log' : The system cannot find the file specified.
----------------
Scan WARNINGS: 1

It's created files like '-20180907 1229 debug.log.7z', but with no content.

@Drew - I have tried that and that didn't work either. I'll post the code and output. — Enigmativity
– Enigmativity, Commented Apr 1, 2019 at 6:01
What is your working directory ? Is it the same where the .log files are ? — Fourat
– Fourat, Commented Apr 1, 2019 at 8:02

nemze · Accepted Answer · 2019-04-01 09:49:45Z

1

Try this:

 $executable = "C:\Program Files\7-Zip\7z.exe"

 dir *.log | % {
    $archive = "$($_.Name).7z"
    $archive
    $source = $_.Name
    $source 
    $oneliner = "a",".\$($archive)",".\$($source)", "-mx4"
    & $executable @oneliner
}

answered Apr 1, 2019 at 9:49

nemze

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3 Comments

Davy de Vries Over a year ago

Add more explanation so the user that asked can understand your answer.

Enigmativity Over a year ago

An explanation would be nice - especially covering the syntax of the $onliner value.

nemze Over a year ago

For $onliner I used method called splatting. More information about running executables in Powershell here.

rokumaru · Accepted Answer · 2019-04-01 07:37:21Z

0

I think it don't needs to be enclosed in quotes.
What if I do the following?

dir *.log | % { &"C:\Program Files\7-Zip\7z.exe" -mx9 a -t7z "$_.7z" $_ }

edited Apr 1, 2019 at 7:37

answered Apr 1, 2019 at 7:24

rokumaru

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Comments

karel · Accepted Answer · 2024-10-07 14:04:25Z

0

7-Zip has a switch for files starting with -.

-- (Stop switches parsing) switch

Disables switch parsing after -- on the command line. This is to allow 7-Zip to use file names that start with -.

edited Oct 7, 2024 at 14:04

karel

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answered Sep 28, 2024 at 8:52

TRDBEI

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