Fish shell compatibility: Execute temp scripts with bash explicitly instead of relying on default shell

[c-0ne]

Description:

When connecting to a system where Fish is the default shell, XPipe fails to establish connections because it generates Bash-syntax temporary scripts (e.g., /tmp/xpipe-XXXXXXXXX.fish) but executes them using the user's default shell.

Current Behavior:

XPipe creates temporary scripts with Bash syntax like:

DELIMITER="-------------------------------------"

These scripts are then executed with the default shell. When Fish is the default shell, this results in syntax errors:

/tmp/xpipe-1246145206.fish (line 2): Unsupported use of '='. In fish, please use 'set DELIMITER "-------------------------------------"'.
DELIMITER="-------------------------------------"
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^

Expected Behavior:
XPipe should execute its temporary scripts using Bash explicitly, regardless of the user's default shell, using one of these approaches:

• Add a shebang line: #!/bin/bash at the top of generated scripts
• Execute scripts explicitly with bash: bash /tmp/xpipe-XXXXXXXXX.fish
• Detect the default shell and generate shell-specific syntax accordingly

Why This Matters:

• Users should be able to keep Fish (or any other non-POSIX shell) as their default shell while still using XPipe. The temporary scripts are internal to XPipe's operation and should not depend on the user's shell preference.

Environment:

• Default shell on target system: Fish
• XPipe version: 20.3

Proposed Solution:
Since XPipe's temporary scripts use Bash syntax, they should be executed with Bash explicitly rather than assuming the default shell is POSIX-compatible.

[crschnick]

I will look into fixing this for v21