In PowerShell, what's the difference between Out-File and Set-Content? Or Add-Content and Out-File -append?
I've found if I use both against the same file, the text is fully mojibaked.
(A minor second question: > is an alias for Out-File, right?)
Here's a summary of what I've deduced, after a few months experience with PowerShell, and some scientific experimentation. I never found any of this in the documentation :(
[Update: Much of this now appears to be better documented.]
Read and write locking
While Out-File is running, another application can read the log file.
While Set-Content is running, other applications cannot read the log file. Thus never use Set-Content to log long running commands.
Encoding
Out-File saves in the Unicode (UTF-16LE) encoding by default (though this can be specified), whereas Set-Content defaults to ASCII (US-ASCII) in PowerShell 3+ (this may also be specified). In earlier PowerShell versions, Set-Content wrote content in the Default (ANSI) encoding.
Editor's note: PowerShell as of version 5.1 still defaults to the culture-specific Default ("ANSI") encoding, despite what the documentation claims. If ASCII were the default, non-ASCII characters such as ü would be converted to literal ?, but that is not the case: 'ü' | Set-Content tmp.txt; (Get-Content tmp.txt) -eq '?' yields $False.
PS > $null | out-file outed.txt
PS > $null | set-content set.txt
PS > md5sum *
f3b25701fe362ec84616a93a45ce9998 *outed.txt
d41d8cd98f00b204e9800998ecf8427e *set.txt
This means the defaults of two commands are incompatible, and mixing them will corrupt text, so always specify an encoding.
Formatting
As Bartek explained, Out-File saves the fancy formatting of the output, as seen in the terminal. So in a folder with two files, the command dir | out-file out.txt creates a file with 11 lines.
Whereas Set-Content saves a simpler representation. In that folder with two files, the command dir | set-content sc.txt creates a file with two lines. To emulate the output in the terminal:
PS > dir | ForEach-Object {$_.ToString()}
out.txt
sc.txt
I believe this formatting has a consequence for line breaks, but I can't describe it yet.
File creation
Set-Content doesn't reliably create an empty file when Out-File would:
In an empty folder, the command dir | out-file out.txt creates a file, while dir | set-content sc.txt does not.
Pipeline Variable
Set-Content takes the filename from the pipeline; allowing you to set a number of files' contents to some fixed value.
Out-File takes the data as from the pipeline; updating a single file's content.
Parameters
Set-Content includes the following additional parameters:
Exclude
Filter
Include
PassThru
Stream
UseTransaction
Out-File includes the following additional parameters:
Append
NoClobber
Width
For more information about what those parameters are, please refer to help; e.g. get-help out-file -parameter append.
Out-File has the behavior of overwriting the output path unless the -NoClobber and/or the -Append flag is set. Add-Content will append content if the output path already exists by default (if it can). Both will create the file if one doesn't already exist.
Another interesting difference is that Add-Content will create an ASCII encoded file by default and Out-File will create a little endian unicode encoded file by default.
> is an alias syntactic sugar for Out-File. It's Out-File with some pre-defined parameter settings.
Well, I would disagree... :)
Out-File has -Append (-NoClober is there to avoid overwriting) that will Add-Content. But this is not the same beast.
command | Add-Content will use .ToString() method on input. Out-File will use default formatting.
so:
ls | Add-Content test.txt
and
ls | Out-File test.txt
will give you totally different results.
And no, '>' is not alias, it's redirection operator (same as in other shells). And has very serious limitation... It will cut lines same way they are displayed. Out-File has -Width parameter that helps you avoid this. Also, with redirection operators you can't decide what encoding to use.
HTH
Bartek
Set-Content supports -Encoding Byte, while Out-File does not.
So when you want to write binary data or result of Text.Encoding#GetBytes() to a file, you should use Set-Content.
Wanted to add about difference on encoding:
Windows with PowerShell 5.1:
Out-File - Default encoding is utf-16le
Set-Content - Default encoding is us-ascii
Linux with PowerShell 7.1:
Out-File - Default encoding is us-ascii
Set-Content - Default encoding is us-ascii
Out-file -append or >> can actually mix two encodings in the same file. Even if the file is originally ASCII or ANSI, it will add Unicode by default to the bottom of it. Add-content will check the encoding and match it before appending. Btw, export-csv defaults to ASCII (no accents), and set-content/add-content to ANSI.
TL;DR, use Set-Content as it's more consistent over Out-File.
Set-Content behavior is the same over different powershell versions
Out-File as #JagWireZ says produces different encodings for the default settings, even on the same OS(Windows) the docs for powershell 5.1 and powershell 7.3 state that the encoding changed from unicode to utf8NoBOM
Some issues like Malformed XML arise from using Out-File, that could of course be fixed by setting the desired encoding, however it's likely to forget to set the encoding and end up with issues.
Related
I'd like to escape \ to \\ in csv file to upload to Redshift.
Following simple PowerShell script can replace $TargetWord \ to $ReplaceWord \\ , as expected, but export utf-8 with bom and sometimes causes the Redshift copy error.
Any advice would be appreciated to improve it. Thank you in advance.
Exp_Escape.ps1
Param(
[string]$StrExpFile,
[string]$TargetWord,
[string]$ReplaceWord
)
# $(Get-Content "$StrExpFile").replace($TargetWord,$ReplaceWord) | Set-Content -Encoding UTF8 "$StrExpFile"
In PowerShell (Core) 7+, you would get BOM-less UTF-8 files by default; -Encoding utf8 and -Encoding utf8NoBom express that default explicitly; to use a BOM, -Encoding utf8BOM is needed.
In Windows PowerShell, unfortunately, you must use a workaround to get BOM-less UTF-8, because -Encoding utf8 only produces UTF-8 files with BOM (and no other utf8-related values are supported).
The workaround requires combining Out-String with New-Item, which (curiously) creates BOM-less UTF-8 files by default even in Windows PowerShell:
Param(
[string]$StrExpFile,
[string]$TargetWord,
[string]$ReplaceWord
)
$null =
New-Item -Force $StrExpFile -Value (
(Get-Content $StrExpFile).Replace($TargetWord, $ReplaceWord) | Out-String
)
Note:
$null = is needed to discard the output object that New-Item emits (which is a file-info object describing the newly created files.
-Force is needed in order to quietly overwrite an existing file by the same name (as Set-Content and Out-File do by default).
The -Value argument must be a single (multi-line) string to write to the file, which is what Out-String ensures.
Caveats:
For non-string input objects, Out-String creates the same rich for-display representations as Out-File and as you would see in the console by default.
New-Item itself does not append a trailing newline when it writes the string to the file, but Out-String curiously does; while this happens to be handy here, it is generally problematic, as discussed in GitHub issue #14444.
The alternative to using Out-String is to create the multi-line string manually, which is a bit more cumbersome ("`n" is used to create LF-only newlines, which PowerShell and most programs happily accept even on Windows; for platform-native newlines (CRLF) on Windows, use [Environment]::NewLine instead):
$null =
New-Item -Force $StrExpFile -Value (
((Get-Content $StrExpFile).Replace($TargetWord, $ReplaceWord) -join "`n`") + "`n"
)
Since the entire file content must be passed as an argument,[1] it must fit into memory as a whole; the convenience function discussed next avoids this problem.
For a convenience wrapper function around Out-File for use in Windows PowerShell that creates BOM-less UTF-8 files, see this answer.
Alternative, with direct use of .NET APIs:
.NET APIs produce BOM-less UTF-8 files by default.
However, because .NET's working directory usually differs from PowerShell's, full file paths must always be used, which requires more effort:
# In order for .NET API calls to work as expected,
# file paths must be expressed as *full, native* paths.
$OutDir = Split-Path -Parent $StrExpFile
if ($OutDir -eq '') { $OutDir = '.' }
$strExpFileFullPath = Join-Path (Convert-Path $OutDir) (Split-Path -Leaf $StrExpFile)
# Note: .NET APIs create BOM-less UTF-8 files *by default*
[IO.File]::WriteAllLines(
$strExpFileFullPath,
(Get-Content $StrExpFile).Replace($TargetWord, $ReplaceWord)
)
The above uses the System.IO.File.WriteAllLines method.
[1] Note that while New-Item technically supports receiving the content to write to the file via the pipeline, it unfortunately writes each to the target file, successively, with only the last one ending up in the file.
I have a script that merges files and that works fine - but characters like åäö looks not good in the output file
Here is the complete script:
$startOfToday = (Get-Date).Date
Get-ChildItem "C:\TEST -include *.* -Recurse |
Where-Object LastWriteTime -gt $startOfToday | ForEach-Object {gc $_; ""} |
Out-File "C:\$(Get-Date -Format 'yyyy/mm/dd').txt"
In the files in looks like this for example
Order ID 1
Order ID 2
This is för får
In the output it gets like this for the last row
Order ID 1
Order ID 2
får för fär
is there a way to make those characters appear in the output file as they appear in the first file?
The implication is that your input files are UTF-8-encoded without a BOM, which in Windows PowerShell are (mis)interpreted to be ANSI-encoded (using the system's active ANSI code page, such as Windows-1252).
The solution is to tell gc (Get-Content) explicitly what encoding to use, via the -Encoding parameter:
Get-ChildItem C:\TEST -include *.* -Recurse |
Where-Object LastWriteTime -gt $startOfToday |
ForEach-Object { Get-Content -Encoding Utf8 $_; ""} |
Out-File "C:\$(Get-Date -Format 'yyyy/mm/dd').txt"
Note that PowerShell never preserves the input encoding automatically, therefore, in the absence of using -Encoding with Out-File, its default encoding is used, which is "Unicode" (UTF-16LE) in Windows PowerShell.
While PowerShell (Core) 7+ also doesn't preserve input encodings, it consistently defaults to BOM-less UTF-8, so your original code would work as-is there.
For more information about default encodings in Windows PowerShell vs. PowerShell (Core) 7+, see this answer.
Note: As AdminOfThings suggests in a comment, simply replacing Out-File with Set-Content in your original code also works in this particular case, because the same misinterpretation of the encoding is then performed on both in- and output, and the data is simply being passed through. This isn't a general solution, however, notably not if you need to process the strings in memory first, before saving them to a file.
I used Tee-Object over the weekend to generate some output of a log file I was tailing, and I tried greping the output file and could not return any results. But the original log file I was able to grep.
It seems that Tee-Object has changed the encoding of the file.
https://adamtheautomator.com/tee-object-powershell/
Is there a setting I can change to just spit out the same encoding it read in to begin with, and also keep the line endings the same?
Short answer no, there is no -Encoding parameter.
From PowerShell Tee-Object documentation:
Tee-Object uses Unicode encoding when it writes to files. As a result,
the output might not be formatted properly in files with a different
encoding. To specify the encoding, use the Out-File cmdlet.
As a workaround, tee to a variable, then use set-content to save it to a file. The default encoding is "ansi".
echo hi | tee -Variable a
set-content file $a
Here's an example, if you want the extra formatting that something like out-file normally provides. I'm guessing, because the original question has no example:
ps cmd | tee -var a
$a | out-string | set-content file
Actually, it looks like tee-object is invoking out-file, so this will set the encoding to ascii for tee-object:
$PSDefaultParameterValues = #{'Out-File:Encoding' = 'Ascii'}
HAL's helpful answer shows that, in Windows PowerShell and as of PowerShell (Core) 7.2.x, Tee-Object does not support specifying an output encoding explicitly when outputting to a file, and instead invariably uses "Unicode" (UTF-16LE) encoding in Windows PowerShell, and (BOM-less) UTF-8 in PowerShell (Core).
GitHub issue #11104 suggests removing this limitation by adding an -Encoding parameter to Tee-Object that allows specifying the desired output encoding.
js2010's answer shows that there actually is an indirect way to control the encoding, via an entry in the default-parameter-value table $PSDefaultParameterValues aimed at Out-File (e.g., $PSDefaultParameterValues['Out-File:Encoding'] = 'utf8').
However, this coupling between Tee-Object and Out-File is an implementation detail, so it is best not to rely on it. (Besides, it's nontrivial to scope it to an individual invocation of Tee-Object).
js2010's answer also is on the right track for a good workaround, by teeing to a variable first, but Set-Content is not the right cmdlet to use to then save the captured objects, because it performs simple .ToString() stringification on its input, whereas Tee-Object - like Out-File - applies PowerShell's rich default formatting.
Therefore, consider the following workaround:
# Tee to a *variable* first ($out)...
$PSVersionTable | Tee-Object -Variable out # | ...
# ... then use Out-File -Encoding to save to a file with the desired encoding
# ; e.g., with UTF-8
Out-File -InputObject $out out.txt -Encoding utf8
As for:
Is there a setting I can change to just spit out the same encoding
No - PowerShell doesn't support that in general: It reads file content into .NET strings in memory, and applies default (or specified) character encoding when saving back to a file.
The only workaround is to determine the input file's encoding manually, and then pass that encoding's name to a write-to-file cmdlet that has an -Encoding parameter, such as Out-File or Set-Content.
As already noted, there is no encoding option for the tee command. To get around this, I was able to use the following for the conversion:
<powershell command> | tee -Variable content
$content | Set-Content -Encoding uft8 test_output.txt
This worked better than the testing I did to try and use Out-File.
In PowerShell, what's the difference between Out-File and Set-Content? Or Add-Content and Out-File -append?
I've found if I use both against the same file, the text is fully mojibaked.
(A minor second question: > is an alias for Out-File, right?)
Here's a summary of what I've deduced, after a few months experience with PowerShell, and some scientific experimentation. I never found any of this in the documentation :(
[Update: Much of this now appears to be better documented.]
Read and write locking
While Out-File is running, another application can read the log file.
While Set-Content is running, other applications cannot read the log file. Thus never use Set-Content to log long running commands.
Encoding
Out-File saves in the Unicode (UTF-16LE) encoding by default (though this can be specified), whereas Set-Content defaults to ASCII (US-ASCII) in PowerShell 3+ (this may also be specified). In earlier PowerShell versions, Set-Content wrote content in the Default (ANSI) encoding.
Editor's note: PowerShell as of version 5.1 still defaults to the culture-specific Default ("ANSI") encoding, despite what the documentation claims. If ASCII were the default, non-ASCII characters such as ü would be converted to literal ?, but that is not the case: 'ü' | Set-Content tmp.txt; (Get-Content tmp.txt) -eq '?' yields $False.
PS > $null | out-file outed.txt
PS > $null | set-content set.txt
PS > md5sum *
f3b25701fe362ec84616a93a45ce9998 *outed.txt
d41d8cd98f00b204e9800998ecf8427e *set.txt
This means the defaults of two commands are incompatible, and mixing them will corrupt text, so always specify an encoding.
Formatting
As Bartek explained, Out-File saves the fancy formatting of the output, as seen in the terminal. So in a folder with two files, the command dir | out-file out.txt creates a file with 11 lines.
Whereas Set-Content saves a simpler representation. In that folder with two files, the command dir | set-content sc.txt creates a file with two lines. To emulate the output in the terminal:
PS > dir | ForEach-Object {$_.ToString()}
out.txt
sc.txt
I believe this formatting has a consequence for line breaks, but I can't describe it yet.
File creation
Set-Content doesn't reliably create an empty file when Out-File would:
In an empty folder, the command dir | out-file out.txt creates a file, while dir | set-content sc.txt does not.
Pipeline Variable
Set-Content takes the filename from the pipeline; allowing you to set a number of files' contents to some fixed value.
Out-File takes the data as from the pipeline; updating a single file's content.
Parameters
Set-Content includes the following additional parameters:
Exclude
Filter
Include
PassThru
Stream
UseTransaction
Out-File includes the following additional parameters:
Append
NoClobber
Width
For more information about what those parameters are, please refer to help; e.g. get-help out-file -parameter append.
Out-File has the behavior of overwriting the output path unless the -NoClobber and/or the -Append flag is set. Add-Content will append content if the output path already exists by default (if it can). Both will create the file if one doesn't already exist.
Another interesting difference is that Add-Content will create an ASCII encoded file by default and Out-File will create a little endian unicode encoded file by default.
> is an alias syntactic sugar for Out-File. It's Out-File with some pre-defined parameter settings.
Well, I would disagree... :)
Out-File has -Append (-NoClober is there to avoid overwriting) that will Add-Content. But this is not the same beast.
command | Add-Content will use .ToString() method on input. Out-File will use default formatting.
so:
ls | Add-Content test.txt
and
ls | Out-File test.txt
will give you totally different results.
And no, '>' is not alias, it's redirection operator (same as in other shells). And has very serious limitation... It will cut lines same way they are displayed. Out-File has -Width parameter that helps you avoid this. Also, with redirection operators you can't decide what encoding to use.
HTH
Bartek
Set-Content supports -Encoding Byte, while Out-File does not.
So when you want to write binary data or result of Text.Encoding#GetBytes() to a file, you should use Set-Content.
Wanted to add about difference on encoding:
Windows with PowerShell 5.1:
Out-File - Default encoding is utf-16le
Set-Content - Default encoding is us-ascii
Linux with PowerShell 7.1:
Out-File - Default encoding is us-ascii
Set-Content - Default encoding is us-ascii
Out-file -append or >> can actually mix two encodings in the same file. Even if the file is originally ASCII or ANSI, it will add Unicode by default to the bottom of it. Add-content will check the encoding and match it before appending. Btw, export-csv defaults to ASCII (no accents), and set-content/add-content to ANSI.
TL;DR, use Set-Content as it's more consistent over Out-File.
Set-Content behavior is the same over different powershell versions
Out-File as #JagWireZ says produces different encodings for the default settings, even on the same OS(Windows) the docs for powershell 5.1 and powershell 7.3 state that the encoding changed from unicode to utf8NoBOM
Some issues like Malformed XML arise from using Out-File, that could of course be fixed by setting the desired encoding, however it's likely to forget to set the encoding and end up with issues.
I am trying to replicate the functionality of the cat command in Unix.
I would like to avoid solutions where I explicitly read both files into variables, concatenate the variables together, and then write out the concatenated variable.
Simply use the Get-Content and Set-Content cmdlets:
Get-Content inputFile1.txt, inputFile2.txt | Set-Content joinedFile.txt
You can concatenate more than two files with this style, too.
If the source files are named similarly, you can use wildcards:
Get-Content inputFile*.txt | Set-Content joinedFile.txt
Note 1: PowerShell 5 and older versions allowed this to be done more concisely using the aliases cat and sc for Get-Content and Set-Content respectively. However, these aliases are problematic because cat is a system command in *nix systems, and sc is a system command in Windows systems - therefore using them is not recommended, and in fact sc is no longer even defined as of PowerShell Core (v7). The PowerShell team recommends against using aliases in general.
Note 2: Be careful with wildcards - if you try to output to inputFiles.txt (or similar that matches the pattern), PowerShell will get into an infinite loop! (I just tested this.)
Note 3: Outputting to a file with > does not preserve character encoding! This is why using Set-Content is recommended.
Do not use >; it messes up the character encoding. Use:
Get-Content files.* | Set-Content newfile.file
In cmd, you can do this:
copy one.txt+two.txt+three.txt four.txt
In PowerShell this would be:
cmd /c copy one.txt+two.txt+three.txt four.txt
While the PowerShell way would be to use gc, the above will be pretty fast, especially for large files. And it can be used on on non-ASCII files too using the /B switch.
You could use the Add-Content cmdlet. Maybe it is a little faster than the other solutions, because I don't retrieve the content of the first file.
gc .\file2.txt| Add-Content -Path .\file1.txt
To concat files in command prompt it would be
type file1.txt file2.txt file3.txt > files.txt
PowerShell converts the type command to Get-Content, which means you will get an error when using the type command in PowerShell because the Get-Content command requires a comma separating the files. The same command in PowerShell would be
Get-Content file1.txt,file2.txt,file3.txt | Set-Content files.txt
I used:
Get-Content c:\FileToAppend_*.log | Out-File -FilePath C:\DestinationFile.log
-Encoding ASCII -Append
This appended fine. I added the ASCII encoding to remove the nul characters Notepad++ was showing without the explicit encoding.
If you need to order the files by specific parameter (e.g. date time):
gci *.log | sort LastWriteTime | % {$(Get-Content $_)} | Set-Content result.log
You can do something like:
get-content input_file1 > output_file
get-content input_file2 >> output_file
Where > is an alias for "out-file", and >> is an alias for "out-file -append".
Since most of the other replies often get the formatting wrong (due to the piping), the safest thing to do is as follows:
add-content $YourMasterFile -value (get-content $SomeAdditionalFile)
I know you wanted to avoid reading the content of $SomeAdditionalFile into a variable, but in order to save for example your newline formatting i do not think there is proper way to do it without.
A workaround would be to loop through your $SomeAdditionalFile line by line and piping that into your $YourMasterFile. However this is overly resource intensive.
To keep encoding and line endings:
Get-Content files.* -Raw | Set-Content newfile.file -NoNewline
Note: AFAIR, whose parameters aren't supported by old Powershells (<3? <4?)
I think the "powershell way" could be :
set-content destination.log -value (get-content c:\FileToAppend_*.log )