Using backslashes to pass a JSON string as a parameter in PowerShell is cumbersome.
executable --json-input '{ \"name\": \"Bob\" }' output.txt
Is there a way to avoid using these backslashes? I tried using single quotes, and doubles quotes in and out without any success. In Python I use triple quotes print(""" here is an example "" """) to avoid character escaping.
Is there a similar solution in PowerShell? One where we never need to worry about reformating a JSON string?
PowerShell has here-strings, similar to the multiline literals from Perl (<<<) or Python (""").
The starting quote must be preceded by @ and immediately followed by a line break, whereas the closing quote must follow a newline and be followed by another @ sign:
command --json-input @"
{ "name": "Bob" }
"@ output.txt
" characters; e.g., '{ "name": "Bob" }. The need for \ escaping embedded " chars. only arises to work around PowerShell's broken argument-passing to external programs up to at least 7.2.x, and it applies whether or not you use here-strings.The unfortunate need for manual \-escaping of " chars. embedded in string arguments passed to external programs is due to a long-standing PowerShell bug - see this answer - which is finally fixed in PowerShell 7.3+, with selective exceptions on Windows - see this answer.
'{ "name": "Bob" }' - no \-escaping, but the bug prevents that.To automate this escaping for now, without having to modify a given JSON string, you can apply a regex-based -replace operation, namely $json -replace '([\\]*)"', '$1$1\"'
# Note: only needed for *external executables*, up to at least PowerShell 7.2.x
executable --json-input ('{ "name": "Bob" }' -replace '([\\]*)"', '$1$1\"') output.txt
Note:
The above replacement operation also handles escaped embedded " characters correctly.
E.g., { "name": "Nat \"King\" Cole" } becomes { \"name\": \"Nat \\\"King\\\" Cole\" }, with the \ before " properly escaped as \\
See this regex101.com page for an explanation of the regex and replacement operation (for technical reasons, the linked page uses C#'s string syntax, but the solution is equivalent to what is shown here).
If you know your JSON input not to contain them, you can simplify to -replace '"', '\"'
-replace '(["\\])','\$1', not -replace '([\\]*)"', '$1$1\"'?\ chars. that directly precede a " in the input string. All other \ instances must be left alone.
\"is not a valid escape sequence in PowerShell - are you perhaps referring to some other shell (bash/zsh/cmd)?