jsh: tail command's -n does not treat - or + in the -n argument correctly

[dantman]

Describe the bug

In the webcontainer terminal the tail commands -n argument does not behave like tail -n [-/+]# in POSIX does when you include a symbol before the number:
https://www.man7.org/linux/man-pages/man1/tail.1p.html

-c number The application shall ensure that the number option-
         argument is a decimal integer, optionally including a
         sign.  The sign shall affect the location in the file,
         measured in bytes, to begin the copying:
            ┌──────┬────────────────────────────────────────┐
            │ Sign │             Copying Starts             │
            ├──────┼────────────────────────────────────────┤
            │  +   │ Relative to the beginning of the file. │
            │  -   │ Relative to the end of the file.       │
            │ none │ Relative to the end of the file.       │
            └──────┴────────────────────────────────────────┘

         The application shall ensure that if the sign of the
         number option-argument is '+', the number option-
         argument is a non-zero decimal integer.

         The origin for counting shall be 1; that is, -c +1
         represents the first byte of the file, -c -1 the last.

-n number This option shall be equivalent to -c number, except the
         starting location in the file shall be measured in lines
         instead of bytes. The origin for counting shall be 1;
         that is, -n +1 represents the first line of the file, -n
         -1 the last.

Link to the blitz that caused the error

https://stackblitz.com/edit/vitejs-vite-evjt7z7u?file=README.md&view=editor

Steps to reproduce

1. Open a webcontainer like https://stackblitz.com/edit/vitejs-vite-evjt7z7u?file=README.md&view=editor
2. Create a test.txt file

   first 1
   first 2
   last 9
   last 8
   last 7
   last 6
   last 5
   last 4
   last 3
   last 2
   last 1
   

3. Run the following commands:
   a.

   # No symbol: Relative to the end of the file.
   tail -n 2 test.txt

   b.

   # negative symbol: Relative to the end of the file.
   tail -n -2 test.txt

   c.

   # positive symbol: Relative to the beginning of the file.
   tail -n +2 test.txt

In webcontainers you will get the result:

❯ # No symbol: Relative to the end of the file.
❯ tail -n 2 test.txt
last 2
last 1

❯ # negative symbol: Relative to the end of the file.
❯ tail -n -2 test.txt
tail: illegal offset -- -2

❯ # positive symbol: Relative to the beginning of the file.
❯ tail -n +2 test.txt
last 2
last 1

Expected behavior

❯ # No symbol: Relative to the end of the file.
❯ tail -n 2 test.txt
last 2
last 1
❯ # negative symbol: Relative to the end of the file.
❯ tail -n -2 test.txt
last 2
last 1
❯ # positive symbol: Relative to the beginning of the file.
❯ tail -n +2 test.txt
first 2
last 9
last 8
last 7
last 6
last 5
last 4
last 3
last 2
last 1

Additional context

I was experimenting in StackBlitz with what would happen if I tried building PostHog's ANTLR grammar with https://www.antlr-ng.org/.

PostHog's package.json is "grammar:build:cpp": "cd posthog/hogql/grammar && cat HogQLLexer.cpp.g4 > HogQLLexer.g4 && tail -n +2 HogQLLexer.common.g4 >> HogQLLexer.g4 && antlr -o ../../../common/hogql_parser -Dlanguage=Cpp HogQLLexer.g4 && rm HogQLLexer.g4 && antlr -o ../../../common/hogql_parser -visitor -no-listener -Dlanguage=Cpp HogQLParser.g4", and I got tripped up when cat HogQLLexer.cpp.g4 > HogQLLexer.g4 && tail -n +2 HogQLLexer.common.g4 >> HogQLLexer.g4 did not behave as it should in StackBlitz.

[bolt-new-by-stackblitz]

Start a new pull request in StackBlitz Codeflow.

• vitejs-vite-evjt7z7u (Open reproduction)