Missing file specification after redirection operator

Question

I got the following error:

| cat << EOF > config.yaml 
|      ~ 
Missing file specification after redirection operator.`

my code in power shell is following

cat << EOF > config.yaml
serve:
  proxy:
    port: 4455 # run the proxy at port 4455
...
EOF

I am running in windows server

As an aside: PowerShell's error message is somewhat confusing here, given that it doesn't support `<` at all (only `>`). However, the _parser_ knows about `<` and with a _syntactically correct_ use of `<` would reveal the non-support; e.g. `cat < foo` would result in error `The '<' operator is reserved for future use.` It is unlikely that it will ever be supported, however. See [this post](https://stackoverflow.com/q/2148746/45375) for what to use instead of `<`. — mklement0, Mar 23 '22 at 14:38

mklement0 · Answer 1 · 2022-03-23T14:18:10.567

It looks like you're mistakenly trying to use bash syntax in PowerShell, namely a here-document.

The PowerShell equivalent, with different syntax, is a here-string.^[1]

The equivalent of the bash statement in your question in PowerShell is:

# PowerShell
@"
serve:
  proxy:
    port: 4455 # run the proxy at port 4455
...
"@ > config.yaml

Note:

Use @' / '@ instead as the delimiters to treat the content verbatim, i.e. to suppress string interpolation, so that $-prefixed tokens aren't interpreted as variable references, for instance. This is the equivalent of quoting (any part of) the EOF delimiter in bash (e.g. cat << 'EOF' ...)
Nothing may follow the opening delimiter (@"/ @') on the same line, and the closing delimiter ("@/ '@) must be at the very start of the line - not even whitespace may precede it.
PowerShell here-strings have no equivalent to the Bash here-document feature of stripping tab-based indentation from the content if the delimiter is prefixed with - (e.g. cat << -EOF).

Windows PowerShell caveats re character encoding:

>, the effective alias of Out-File, defaults to "Unicode" (UTF-16LE) in Windows PowerShell (by contrast, in PowerShell (Core) (v6+) the consistent default, across all cmdlets, is BOM-less UTF-8).
To control the character encoding, call Out-File - or, with text input, preferably - Set-Content with the -Encoding parameter.
- E.g., replace > config.yaml with | Set-Content -Encoding Ascii config.yaml
- However, note that if you need UTF-8 encoding, -Encoding utf8 will invariably create a file with a BOM in Windows PowerShell (but not in PowerShell (Core), as noted); to avoid that, direct use of .NET APIs is needed - see this answer.

^{[1] Not to be confused with bash's here-strings, <<<"...", which are a single-line alternative to here-documents.}

1 Answers1