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@aisamanra
Created March 27, 2015 21:05
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wrapper script for switching between and installing different GHC versions
#!/bin/bash -e
# ghc wrapper script (for managing installed GHC versions)
# this is a small script I use that allows multiple simultaneous ghc
# installations. This makes the following assumptions about how
# you want to set up your system:
# - GHC version {X} is installed with prefix ~/install/ghc-${X}
# - A file naming the current selected GHC version is placed
# at ~/.current-ghc
# - cabal is configured to point to this script instead of ghc
# - If using fetch, then mktemp must result in a directory to which
# this script can write, as well
# This script is being run as a user that can read and modify things
# in your $HOME directory.
if [[ "$1" = "list" ]]; then
for f in $(ls ~/install/ | grep ghc); do
# It's possible (for various reasons) for /none/ of the
# current versions to be selected, in which case all of
# them will be prefixed by a -; otherwise, the one that
# is selected will be prefixed by a +.
if [[ "$f" = "$(cat ~/.current-ghc)" ]]; then
echo "+" $f
else
echo "-" $f
fi
done
elif [[ "$1" = "set" ]]; then
MATCHES=($(ls ~/install | grep ghc | grep -e "$2"))
if [[ -z $MATCHES ]]; then
# There is nothing in ~/install that matches that version
echo "Unknown GHC version: $2"
elif [ "${#MATCHES[@]}" -eq "1" ]; then
# There is exactly one relevant match---we can use that one!
echo "Setting GHC version to $MATCHES"
echo $MATCHES >~/.current-ghc
else
# The regex given matches too many versions.
echo "Ambiguous GHC version: argument matches"
for f in "${MATCHES[@]}"; do
echo " " $f
done
fi
elif [[ "$1" = "fetch" ]]; then
VERSION="$2"
URL="https://www.haskell.org/ghc/dist/$VERSION/ghc-$VERSION-src.tar.xz"
LOC=$(mktemp -d)
(
echo "Attempting to fetch $URL..." &&
curl -L "$URL" >"$LOC/ghc.tar.xz" &&
cd "$LOC" &&
echo "...tarball fetched; unpacking..." &&
tar -xf "ghc.tar.xz" &&
cd "$LOC/ghc-$VERSION" &&
echo "Creating $HOME/install/ghc-$VERSION" &&
mkdir -p "$HOME/install/ghc-$VERSION" &&
./configure --prefix="$HOME/install/ghc-$VERSION" &&
echo "... starting build process..." &&
make &&
make install &&
echo "...finished!"
)
elif [[ "$1" = "--wrapper-help" ]]; then
cat <<EOF
$0 [wrapper script]
Usage:
$0 list List installed versions of ghc
$0 set [regex] Set current GHC to the version that uniquely
matches the supplied regex
$0 fetch [version] Fetch, build, and install the specified version
of GHC. (Does not change the current version.)
$0 --wrapper-help See this help menu
$0 [anything else] Use GHC normally
This wrapper script assumes that you'll always install your GHC versions
to ~/install/ghc-{VERSION}, and will store the currently selected GHC version
in ~/.current-ghc.
WARNING: This script is quite brittle and makes a lot of assumptions about
how you lay things out! While I suspect it shouldn't actively break anything,
be careful about using it!
EOF
else
exec /home/gdritter/install/$(cat ~/.current-ghc)/bin/$(basename $0) "$@"
fi
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