As some of you know, I have made a programming language, called AEC, and written two compilers for it, one targetting x86 and other targetting WebAssembly. Recently, I have tried to write two shell scripts to download, compile and use those compilers, and run the Analog Clock example. I have put those two shell scripts on my blog, and it is important for me that they run on as many computers as possible. Here is what I've made by now.
Shell script to use the AEC-to-x86 compiler:

mkdir ArithmeticExpressionCompiler
cd ArithmeticExpressionCompiler
if [ $(command -v wget > /dev/null 2>&1 ; echo $?) -eq 0 ] # Check if "wget" exists, see those StackOverflow answers for more details:
                                                                                         # https://stackoverflow.com/a/75103891/8902065
                                                                                         # https://stackoverflow.com/a/75103209/8902065
then
  wget https://flatassembler.github.io/Duktape.zip
else
  curl -o Duktape.zip https://flatassembler.github.io/Duktape.zip
fi
unzip Duktape.zip
if [ $(command -v clang > /dev/null 2>&1 ; echo $?) -eq 0 ] # We prefer "clang" to "gcc" because... what if somebody tries to run this in CygWin terminal? GCC will not work then, CLANG might.
then
  c_compiler="clang"
else
  c_compiler="gcc"
fi
$c_compiler -o aec aec.c duktape.c -lm # The linker that comes with recent versions of Debian Linux insists that "-lm" is put AFTER the source files, or else it outputs some confusing error message.
if [ "$OS" = "Windows_NT" ]
then
  ./aec analogClockForWindows.aec
  $c_compiler -o analogClockForWindows analogClockForWindows.s -m32
  ./analogClockForWindows
else
  ./aec analogClock.aec
  $c_compiler -o analogClock analogClock.s -m32
  ./analogClock
fi
        

Shell script to use the AEC-to-WebAssembly compiler:

if [ $(command -v git > /dev/null 2>&1 ; echo $?) -eq 0 ]
then
  git clone https://github.com/FlatAssembler/AECforWebAssembly.git
  cd AECforWebAssembly
elif [ $(command -v wget > /dev/null 2>&1 ; echo $?) -eq 0 ]
then
  mkdir AECforWebAssembly
  cd AECforWebAssembly
  wget https://github.com/FlatAssembler/AECforWebAssembly/archive/refs/heads/master.zip
  unzip master.zip
  cd AECforWebAssembly-master
else
  mkdir AECforWebAssembly
  cd AECforWebAssembly
  curl -o AECforWebAssembly.zip -L https://github.com/FlatAssembler/AECforWebAssembly/archive/refs/heads/master.zip # Without the "-L", "curl" will store HTTP Response headers of redirects to the ZIP file instead of the actual ZIP file.
  unzip AECforWebAssembly.zip
  cd AECforWebAssembly-master
fi
if [ $(command -v g++ > /dev/null 2>&1 ; echo $?) -eq 0 ]
then
  g++ -std=c++11 -o aec AECforWebAssembly.cpp # "-std=c++11" should not be necessary for newer versions of "g++". Let me know if it is, as that probably means I disobeyed some new C++ standard (say, C++23).
else
  clang++ -o aec AECforWebAssembly.cpp
fi
cd analogClock
../aec analogClock.aec
npx -p wabt wat2wasm analogClock.wat
if [ "$OS" = "Windows_NT" ] # https://stackoverflow.com/a/75125384/8902065
                            # https://www.reddit.com/r/bash/comments/10cip05/comment/j4h9f0x/?utm_source=share&utm_medium=web2x&context=3
then
  node_version=$(node.exe -v)
else # We are presumably running on an UNIX-like system, where storing output of some program into a variable works as expected.
  node_version=$(node -v)
fi
# "node -v" outputs version in the format "v18.12.1"
node_version=${node_version:1} # Remove 'v' at the beginning
node_version=${node_version%\.*} # Remove trailing ".*".
node_version=${node_version%\.*} # Remove trailing ".*".
node_version=$(($node_version)) # Convert the NodeJS version number from a string to an integer.
if [ $node_version -lt 11 ]
then
  echo "NodeJS version is lower than 11 (it is $node_version), you will probably run into trouble!"
fi
node analogClock
        

So, what do you think, how can I improve those shell scripts? The most important thing for me is that they run on as many computers as possible, simply by being copied-and-pasted into a terminal emulator.