✏ EDIT: install.sh

#!/bin/sh

# A word about this shell script:
#
# It must work everywhere, including on systems that lack
# a /bin/bash, map 'sh' to ksh, ksh97, bash, ash, or zsh,
# and potentially have either a posix shell or bourne
# shell living at /bin/sh.
#
# See this helpful document on writing portable shell scripts:
# https://www.gnu.org/s/hello/manual/autoconf/Portable-Shell.html
#
# The only shell it won't ever work on is cmd.exe.

if [ "x$0" = "xsh" ]; then
  # run as curl | sh
  # on some systems, you can just do cat>npm-install.sh
  # which is a bit cuter.  But on others, &1 is already closed,
  # so catting to another script file won't do anything.
  # Follow Location: headers, and fail on errors
  curl -f -L -s https://www.npmjs.org/install.sh > npm-install-$$.sh
  ret=$?
  if [ $ret -eq 0 ]; then
    (exit 0)
  else
    echo "Uninstalling npm-install-$$.sh" >&2
    rm npm-install-$$.sh
    echo "Failed to download script" >&2
    exit $ret
  fi
  sh npm-install-$$.sh
  ret=$?
  echo "Uninstalling npm-install-$$.sh" >&2
  rm npm-install-$$.sh
  exit $ret
fi

# See what "npm_config_*" things there are in the env,
# and make them permanent.
# If this fails, it's not such a big deal.
configures="`env | grep 'npm_config_' | sed -e 's|^npm_config_||g'`"

npm_config_loglevel="error"
if [ "x$npm_debug" = "x" ]; then
  (exit 0)
else
  echo "Running in debug mode."
  echo "Note that this requires bash or zsh."
  set -o xtrace
  set -o pipefail
  npm_config_loglevel="verbose"
fi
export npm_config_loglevel

# make sure that node exists
node=`which node 2>&1`
ret=$?
# if not found, try "nodejs" as it is the case on debian
if [ $ret -ne 0 ]; then
  node=`which nodejs 2>&1`
  ret=$?
fi
if [ $ret -eq 0 ] && [ -x "$node" ]; then
  (exit 0)
else
  echo "npm cannot be installed without node.js." >&2
  echo "Install node first, and then try again." >&2
  echo "" >&2
  echo "Maybe node is installed, but not in the PATH?" >&2
  echo "Note that running as sudo can change envs." >&2
  echo ""
  echo "PATH=$PATH" >&2
  exit $ret
fi

# set the temp dir
TMP="${TMPDIR}"
if [ "x$TMP" = "x" ]; then
  TMP="/tmp"
fi
TMP="${TMP}/npm.$$"
rm -rf "$TMP" || true
mkdir "$TMP"
if [ $? -ne 0 ]; then
  echo "failed to mkdir $TMP" >&2
  exit 1
fi

BACK="$PWD"

ret=0
tar="${TAR}"
if [ -z "$tar" ]; then
  tar="${npm_config_tar}"
fi
if [ -z "$tar" ]; then
  tar=`which tar 2>&1`
  ret=$?
fi

if [ $ret -eq 0 ] && [ -x "$tar" ]; then
  echo "tar=$tar"
  if [ $tar --version > /dev/null 2>&1 ]; then
    echo "version:"
    $tar --version
  fi
  ret=$?
fi

if [ $ret -eq 0 ]; then
  (exit 0)
else
  echo "No suitable tar program found."
  exit 1
fi

# Try to find a suitable make
# If the MAKE environment var is set, use that.
# otherwise, try to find gmake, and then make.
# If no make is found, then just execute the necessary commands.

# XXX For some reason, make is building all the docs every time.  This
# is an annoying source of bugs. Figure out why this happens.
MAKE=NOMAKE

if [ "x$MAKE" = "x" ]; then
  make=`which gmake 2>&1`
  if [ $? -eq 0 ] && [ -x "$make" ]; then
    (exit 0)
  else
    make=`which make 2>&1`
    if [ $? -eq 0 ] && [ -x "$make" ]; then
      (exit 0)
    else
      make=NOMAKE
    fi
  fi
else
  make="$MAKE"
fi

if [ -x "$make" ]; then
  (exit 0)
else
  # echo "Installing without make. This may fail." >&2
  make=NOMAKE
fi

# If there's no bash, then don't even try to clean
if [ -x "/bin/bash" ]; then
  (exit 0)
else
  clean="no"
fi

node_version=`"$node" --version 2>&1`
ret=$?
if [ $ret -ne 0 ]; then
  echo "You need node to run this program." >&2
  echo "node --version reports: $node_version" >&2
  echo "with exit code = $ret" >&2
  echo "Please install node before continuing." >&2
  exit $ret
fi

t="${npm_install}"
if [ -z "$t" ]; then
  # switch based on node version.
  # note that we can only use strict sh-compatible patterns here.
  case $node_version in
    0.[01234567].* | v0.[01234567].*)
      echo "You are using an outdated and unsupported version of" >&2
      echo "node ($node_version).  Please update node and try again." >&2
      exit 99
      ;;
    *)
      echo "install npm@latest"
      t="latest"
      ;;
  esac
fi

# need to echo "" after, because Posix sed doesn't treat EOF
# as an implied end of line.
url=`(curl -SsL https://registry.npmjs.org/npm/$t; echo "") \
     | sed -e 's/^.*tarball":"//' \
     | sed -e 's/".*$//'`

ret=$?
if [ "x$url" = "x" ]; then
  ret=125
  # try without the -e arg to sed.
  url=`(curl -SsL https://registry.npmjs.org/npm/$t; echo "") \
       | sed 's/^.*tarball":"//' \
       | sed 's/".*$//'`
  ret=$?
  if [ "x$url" = "x" ]; then
    ret=125
  fi
fi
if [ $ret -ne 0 ]; then
  echo "Failed to get tarball url for npm/$t" >&2
  exit $ret
fi

echo "fetching: $url" >&2

cd "$TMP" \
  && curl -SsL "$url" \
     | $tar -xzf - \
  && cd "$TMP"/* \
  && (ret=0
      if [ $ret -ne 0 ]; then
        echo "Aborted 0.x cleanup.  Exiting." >&2
        exit $ret
      fi) \
  && (if [ "x$configures" = "x" ]; then
        (exit 0)
      else
        echo "./configure $configures"
        echo "$configures" > npmrc
      fi) \
  && (if [ "$make" = "NOMAKE" ]; then
        (exit 0)
      elif "$make" uninstall install; then
        (exit 0)
      else
        make="NOMAKE"
      fi
      if [ "$make" = "NOMAKE" ]; then
        "$node" bin/npm-cli.js rm npm -gf
        "$node" bin/npm-cli.js install -gf $("$node" bin/npm-cli.js pack | tail -1)
      fi) \
  && cd "$BACK" \
  && rm -rf "$TMP" \
  && echo "It worked"

ret=$?
if [ $ret -ne 0 ]; then
  echo "It failed" >&2
fi
exit $ret

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