Why does this shell script with sbcl --version print a newline before the echo output?

Question

The following script prints a newline before the first word printed by echo. Why?

Environment:

• macOS Mojave
• using either system sh (which is GNU bash 3.2.57(1), or GNU bash 5.1.8(1)

Description

Here's the script, which I tried with different shebang lines (bash or sh) ending with the same problem:

#!/bin/sh
which sbcl  > /dev/null
status=$?
if [ $status -eq 0 ]; then
    export PGMFOR_LISP=`which sbcl`
    echo -1-
    echo "Using Common Lisp - " `sbcl --version` "- from:" $PGMFOR_LISP
    echo -2-
else
    echo "**Error!** Request to use SBCL, but fail to find it in PATH!"
fi

It prints the following:

-1-

Using Common Lisp -  SBCL 2.1.4 - from: /usr/local/bin/sbcl
-2-

The issue I have is the empty line between the -1- line and the Using Common Lisp ... line.

The above uses sbcl --version to get the version. It prints on stdout and does print a newline before the string it outputs. I assume the problem comes from that, but I have not been able to fix it with tr -d for example.

Here's the following extra tests:

>Pierres-iMac@Fri May 14@07:25:39[~]
> sbcl --version 2>/dev/null | od -tc
0000000    S   B   C   L       2   .   1   .   4  \n                    
0000013

>Pierres-iMac@Fri May 14@07:26:06[~]
> sbcl --version 2>/dev/null | hexdump
0000000 53 42 43 4c 20 32 2e 31 2e 34 0a               
000000b

>Pierres-iMac@Fri May 14@07:30:19[~]
> 

How can I get rid of that extra empty line?

Answer 1

# source me
if which sbcl >/dev/null
then
    export PGMFOR_LISP=`which sbcl`
    printf "%s\n" '-1-'
    printf "Using Common Lisp - %s - from %s\n" "$(sbcl --version 2>/dev/null)" "$PGMFOR_LISP"
    printf "%s\n" '-2-'
else
    echo '**Error!** Request to use SBCL, but fail to find it in PATH!'
fi

There's little point having an initial #! line because this script can only usefully be sourced (possibly with ., again depending on the shell).

I've replaced the echo -1- type lines because using echo with an argument that starts with a dash is not well defined - different shells will do different things.

---

For the purposes of testing the apparently strange behaviour of sbcl --version, I've used this mockup test script, executable and in my $PATH:

#!/bin/bash
echo >&2
echo "SBCL 2.1.4"

I cannot reproduce the extra blank line you're reporting

export PGMFOR_LISP=`which sbcl`
printf "Using Common Lisp - %s - from %s\n" "$(sbcl --version 2>/dev/null)" "$PGMFOR_LISP"

results in just the single line

Using Common Lisp - SBCL 2.1.4 - from /home/roaima/bin/sbcl