git-swapid

#!/bin/sh
#
# Script to swap git/ssh identities.
# It affects two files:
#    ~/.gitconfig
#    ~/.ssh/config
#
# You need at least two private RSA keys for your identity.
# I assume that your keys are stored in:
#
#        /home/john/.ssh/john
#        /home/john/.ssh/peter
#
#
# All your identities are stored within .gitconfig.
#
# Add your adentities to your ~/.gitconfig file like in the following listing.
# Every login has to be exactly the same as its key given in [identity "..."].
# If you define identity [identity "foo"] its login has to be "foo".
#
#    # extract from ~/.gitconfig
#    [identity "john"]
#        name = John Doe
#        email = john@example.net
#        key = /home/john/.ssh/john
#        login = john
#
#    [identity "peter"]
#        name = Peter Nobody
#        email = peter@some.other.host.example.com
#        key = /home/john/.ssh/peter
#        login = peter
#
#
# Swapid entry is appended at the end of .ssh/config.
# It will be the last effort entry.
# If you have .ssh/config entries like in:
#
#    # extract from ~/config
#    Host some-label
#        HostName example.com
#        User john
#        IdentityFile ~/.ssh/john_id_rsa
#
#    Host lorem
#        HostName ipsum.com
#        User sarah
#        IdentityFile ~/.ssh/sarah_id_rsa
#
#    Host *
#        IdentityFile ~/.ssh/another_id_rsa
#
# Then:
#    ssh -T some-label            --> john@example.com using john_id_rsa
#    ssh -T lorem                 --> sarah@ipsum.com using sarah_id_rsa
#    ssh -T me@ble                --> me@ble using another_id_rsa
#
# (C) 2013 gajdaw
#

if [ "$#" -gt 1 ]; then
    echo "***** ERROR: Too many arguments!"
    exit
fi;

if [ "$#" -eq 1 ]; then
    MYID=$1
else
    # set default identity if possible
    MYID=`git config --global user.login`

    if [ ! $MYID ]; then
        echo "***** ERROR: Global user.login not set!"
        echo "***** ERROR: git swapid called without parameters needs default identity!"
        exit
    fi;
fi;

if [ ! $MYID ]; then
    echo "***** ERROR: The identity cannot be a null string!"
    exit
fi;

USER_NAME=`git config --global user.name`
USER_EMAIL=`git config --global user.email`
USER_LOGIN=`git config --global user.login`

MYID_NAME=`git config --global identity.$MYID.name`
MYID_EMAIL=`git config --global identity.$MYID.email`
MYID_KEY=`git config --global identity.$MYID.key`
MYID_LOGIN=`git config --global identity.$MYID.login`

echo "Configuration read from ~/.gitconfig"
echo "    user.name     = $USER_NAME"
echo "    user.email    = $USER_EMAIL"
echo "    user.login    = $USER_LOGIN"
echo "  "
echo "    identity.$MYID.name     = $MYID_NAME"
echo "    identity.$MYID.email    = $MYID_EMAIL"
echo "    identity.$MYID.key      = $MYID_KEY"
echo "    identity.$MYID.login    = $MYID_LOGIN"
echo "  "
echo "Configuration read from ~/.ssh/config"
grep -E "^       IdentityFile                         [^ ;]*$" ~/.ssh/config
echo "  "


#if [ "$MYID_NAME $MYID_EMAIL $MYID_KEY $MYID_LOGIN" == "   " ]; then
#    echo "    * Initialazing $MYID identity"
#    git config --global identity.$MYID.name "John Doe"
#    git config --global identity.$MYID.email john@example.net
#    git config --global identity.$MYID.key ~/.ssh/john_id_rsa
#    git config --global identity.$MYID.login $MYID

#    MYID_NAME=`git config --global identity.$MYID.name`
#    MYID_EMAIL=`git config --global identity.$MYID.email`
#    MYID_KEY=`git config --global identity.$MYID.key`
#    MYID_LOGIN=`git config --global identity.$MYID.login`
#fi;


# We expect all four not null global git config settings for this id
if [ ! "$MYID_NAME" ]; then
    echo "***** ERROR: Problem with git global configuration: identity.$MYID.name"
    echo " "
    echo "You can set it with:"
    echo "    \$ git config --global identity.$MYID.name \"John Doe\""
    exit;
fi
if [ ! $MYID_EMAIL ]; then
    echo "***** ERROR: Problem with git global configuration: identity.$MYID.email"
    echo " "
    echo "You can set it with:"
    echo "    \$ git config --global identity.$MYID.email john@example.net"
    exit;
fi
if [ ! $MYID_KEY ]; then
    echo "***** ERROR: Problem with git global configuration: identity.$MYID.key"
    echo " "
    echo "You can set it with:"
    echo "    \$ git config --global identity.$MYID.key ~/.ssh/john_id_rsa"
    exit;
fi
if [ ! $MYID_LOGIN ]; then
    echo "***** ERROR: Problem with git global configuration: identity.$MYID.login"
    echo " "
    echo "You can set it with:"
    echo "    \$ git config --global identity.$MYID.login $MYID"
    exit;
fi

if [ ! -f $MYID_KEY ]; then
    echo "***** ERROR: The private key does not exist!"
    echo "***** ERROR: Filename: $MYID_KEY"
    echo ""
fi

if [ ! $MYID_LOGIN == $MYID ]; then
    git config --global identity.$MYID.login $MYID
    MYID_LOGIN=$MYID
    echo "    * Resetting LOGIN in ~/.gitconfig for $MYID"
fi

# without parameters only print current settings
if [ "$#" -eq 0 ]; then
    exit
fi;

# Everything is fine. Swap the identity

# swap global git config
git config --global user.name "$MYID_NAME"
git config --global user.email $MYID_EMAIL
git config --global user.login $MYID_LOGIN


# swap private key in .ssh/config
SSH_CONFIG_LINE="       IdentityFile                         $MYID_KEY"
ESCAPED="$(echo "$SSH_CONFIG_LINE" | sed -e 's/[\/&]/\\&/g')"

# does the .ssh/config exists?
if [ ! -f ~/.ssh/config ]; then
    echo "    * Creating ~/.ssh/config"
    echo "#swapid" > ~/.ssh/config
    echo "Host *" >> ~/.ssh/config
    echo "$SSH_CONFIG_LINE" >> ~/.ssh/config
else

    # Does ~/.ssh/config contain our IdentityFile?
    WASIUSED=`grep -E "^       IdentityFile                         [^ ;]*$" ~/.ssh/config | wc -l`
    if [ $WASIUSED -eq 0 ]; then
        # no, there isn't IdentityFile entry matching swapid RE in .ssh/config
        echo "***** ERROR: Was .ssh/config used by swapid before?"
        echo "***** ERROR: Check .ssh/config  - look for #IdentityFile"

        # Is there a commented IdentityFile line?
        WASIUSED_COMMENTED=`grep -E "^#       IdentityFile                         [^ ;]*$" ~/.ssh/config | wc -l`
        if [ $WASIUSED_COMMENTED -eq 0 ]; then

            echo "#swapid" >> ~/.ssh/config
            echo "Host *" >> ~/.ssh/config
            echo "$SSH_CONFIG_LINE" >> ~/.ssh/config
        else
            # modify commented IdentityFile line with new id
            sed -i "s/^#       IdentityFile                         [^ ;]*$/#$ESCAPED/g" ~/.ssh/config
        fi;
    else
        # yes, there is IdentityFile entry matching RE in .ssh/config
        echo "    * Modifying ~/.ssh/config"
        sed -i "s/^       IdentityFile                         [^ ;]*$/$ESCAPED/g" ~/.ssh/config
    fi;
fi;