PowerShell: Preserve Newlines in Expandable Strings

Why PowerShell Removes Newlines in Expandable Strings and How to Fix It

In PowerShell, when you wrap a command in an expandable string like "$(hledger accounts --directive --types)", the newlines are automatically removed because PowerShell converts the command’s output into a single continuous string. This happens because expandable strings process all output as text and don’t preserve the original line formatting that PowerShell displays when running commands directly.

To preserve newlines, you need to use specific techniques that tell PowerShell to maintain the original formatting:

Contents

• Why PowerShell Removes Newlines
• Solution 1: Using the Join Operator
• Solution 2: Using the -Raw Parameter
• Solution 3: Using Out-String
• Solution 4: Here-String Approach
• Best Practices and Recommendations

Why PowerShell Removes Newlines in Expandable Strings

When you run a command directly in PowerShell, like:

hledger accounts --directive --types

PowerShell’s output formatting system handles the display, preserving line breaks and spacing. However, when you capture the same command output in an expandable string:

"$(hledger accounts --directive --types)"

PowerShell treats the output as a single string and processes it through its string expansion mechanism, which collapses consecutive whitespace characters (including newlines) into spaces. This is why your output becomes a continuous line of text instead of maintaining the original formatting.

Solution 1: Using the Join Operator

The most straightforward approach is to use the -join operator with the newline character "n"`:

$hledgerAccounts = (hledger accounts --directive --types) -join "`n"

This method:

1. Captures the command output as an array of lines
2. Explicitly joins them with newline characters
3. Preserves the original formatting when the string is used

Note: The parentheses around the command are important to ensure the command executes first before joining the results.

Solution 2: Using the -Raw Parameter

Another effective solution is to use the -Raw parameter with Invoke-Expression:

$hledgerAccounts = Invoke-Expression -Command "hledger accounts --directive --types" -Raw

The -Raw parameter tells PowerShell to treat the command output as a single raw string without additional processing, which helps preserve the original formatting including newlines.

This approach is particularly useful when you need to maintain the exact output as displayed in the console.

Solution 3: Using Out-String

The Out-String cmdlet converts objects to strings while preserving formatting:

$hledgerAccounts = hledger accounts --directive --types | Out-String

This method:

• Preserves the exact visual representation of the output
• Maintains newlines and other formatting elements
• Works well for commands that produce text-based output

You can also use the -Stream parameter if you need to process the output line by line while still preserving the formatting:

$hledgerAccounts = hledger accounts --directive --types | Out-String -Stream

Solution 4: Here-String Approach

For certain use cases, here-strings can be helpful:

$hledgerAccounts = @'
$(hledger accounts --directive --types)
'@

However, this approach might still have some formatting issues depending on how PowerShell processes the here-string, and it’s generally not as reliable as the previous methods for preserving exact formatting.

Best Practices and Recommendations

When working with command output in PowerShell that needs to preserve formatting:

1. Choose the right method for your use case:

   • For exact console output preservation, use Out-String
   • For explicit control over line joining, use -join "n"`
   • For raw command capture, use -Raw parameter

2. Be aware of method differences:

   • Out-String might add extra blank lines at the end
   • -join method gives you more control but requires explicit newline handling
   • -Raw parameter provides the most direct capture of command output

3. Test your output:

   • Always verify that the preserved formatting meets your requirements
   • Check for any unintended whitespace or formatting artifacts

4. Consider how the output will be used:

   • If displaying to console, Out-String or -Raw might be best
   • If processing programmatically, the -join method offers more flexibility

The most reliable solution for your specific case would be:

$hledgerAccounts = hledger accounts --directive --types | Out-String

This preserves the exact formatting including newlines as displayed when running the command directly.