A script for linking dot files into a home directory.

install.sh

#!/bin/bash

# install.sh
# Author: George Lesica <glesica@gmail.com>
# Description: Deploy script for my dotfiles repo.
# License: Public Domain (where it exists), any OSI-approved 
# license elsewhere.

#
# Configuration
#

repo="`pwd`"
src="${repo}/home"
manifest="${repo}/manifest"
target="$HOME"

#
# Defaults
#

do_backup=1     # Back up existing files. Default: true.
do_copy=0       # Copy instead of symlinking files. Default: false.
do_continue=0   # Continue on error instead of exit
do_help=0       # Display the help message. Default: false.
do_silent=0     # Suppress all output to stdout. Default: false.
do_test=0       # Testing mode, don't make changes. Default: false.
do_verbose=0    # Produce extra output. Default: false.
do_yes=0        # Assume "yes" to all queries. Default: false.

#
# Constants
#

PROGNAME=$(basename $0)

#
# Helper Functions
#

# Error printer
function error_echo() {
    echo "${PROGNAME}: ${1:-"Unknown error"}" 1>&2
}
    
# Error output function
function error_exit() {
    error_echo "$1"
    exit 1
}

# Conditional echo that checks $do_verbose.
function verbose_echo() {
    if (( $do_verbose )); then
        echo $1
    fi
}

# Conditional echo that checks $do_silent.
function silent_echo() {
    if (( ! $do_silent )); then
        echo $1
    fi
}

# Back up an existing dot file.
# Return codes:
#   0 - successfully backed up file/dir
#   1 - received a blank argument
#   2 - move command failed
function backup() {
    # Exit on blank argument.
    if [ -z "$1" ]; then
        error_echo "Empty backup target given"
        return 1
    fi

    # Announce
    verbose_echo "Backing up ${target}/.${1}"

    # Return successfully if file/dir does not exist.
    if [ ! -e "${target}/.${1}" ]; then
        silent_echo "File ${target}/.${1} does not exist, no backup created"
        return 0
    fi

    # Safely rename the file as a backup.
    local i=0
    while [ -e "${target}/.${1}.backup${i}" ]; do
        i=$[$i+1]
    done

    # Move the file to its backup location.
    silent_echo "File ${target}/.${1} exists. Backing up as ${target}/.${1}.backup${i}"
    if (( ! $do_test )); then
        mv "${target}/.${1}" "${target}/.${1}.backup${i}"
        if [ "$?" -ne 0 ]; then
            return 2
        fi
    else
        silent_echo "Test mode, no action taken"
    fi
    return 0
}

# Link or copy a file or directory into the target location.
# Return codes:
#   0 - successfully handled file/dir
#   1 - received a blank argument
#   2 - source file does not exist
#   3 - backup failed
#   4 - copy or link command failed
function install() {
    # Exit on a blank argument.
    if [ -z "$1" ]; then
        error_echo "Empty install target given"
        return 1
    fi

    # Announce ourselves.
    verbose_echo "Installing ${1}"

    # Check if file exists in source.
    if [ ! -e "${src}/${1}" ]; then
        error_echo "File ${src}/${1} does not exist"
        return 2
    fi

    # Determine whether we should handle the file/dir.
    local proceed="Yes"
    if (( ! $do_silent )) && (( ! $do_yes )); then
        echo "Install file ${1}?"
        select proceed in "Yes" "No"; do
            break;
        done
    fi

    # Return successfully if we were instructed to skip the file/dir.
    if [ "$proceed" != "Yes" ]; then
        verbose_echo "Skipping ${1} per user request"
        return 0
    fi

    # Back up the existing version of the file/dir.
    if (( $do_backup )); then
        backup "$1"
        if [ "$?" -ne 0 ]; then
            error_echo "Backup of ${1} failed"
            return 3
        fi
    fi
 
    # Copy or symlink the file/dir into the target.
    if (( $do_copy )); then
        silent_echo "Copying file ${src}/${1} to ${target}/.${1}"
        if (( ! $do_test )); then
            cp -R "${src}/${1}" "${target}/.${1}";
            if [ "$?" -ne 0 ]; then
                error_echo "Copying ${1} failed"
                return 4
            fi
        else
            silent_echo "Test mode, no action taken"
        fi
    else
        silent_echo "Symlinking file ${src}/${1} to ${target}/.${1}"
        if (( ! $do_test )); then
            ln -sf "${src}/${1}" "${target}/.${1}";
            if [ "$?" -ne 0 ]; then
                error_echo "Symlinking ${1} failed"
                return 4
            fi
        else
            silent_echo "Test mode, no action taken"
        fi
    fi

    return 0
}

# Install a list of files.
function install_all() {
    # Make sure the manifest file exists.
    if [ ! -f ${manifest} ]; then
        error_exit "Invalid source location. No manifest found"
    fi

    # Install each item in the manifest.
    for f in `cat ${manifest}`; do
        install "${f}"
        if [ "$?" -ne 0 ]; then
            local msg="Error processing ${f}"
            if (( ! $do_continue )); then
                error_exit "$msg"
            else
                error_echo "$msg"
            fi
        fi
    done

    return 0
}

# Print help information.
function help() {
    echo "Usage: ${PROGNAME} -[bchstvy] [-m <manifest>] [-r <src>] [-d <destination>]"
    echo "A script to install dot files into /home (or elsewhere) from a common location based on a manifest file."
    echo "    -b : Skip creating backups of existing files"
    echo "    -c : Copy instead of symlinking new files"
    echo "    -e : Continue processing manifest even if errors occur"
    echo "    -h : Display this help message and exit"
    echo "    -s : Suppress all non-error output"
    echo "    -t : Test run, do not modify files or directories"
    echo "    -v : Be extra verbose, lots of output"
    echo "    -y : Automatically answer 'yes' to all queries"
    echo "    -m <manifest> : Read list of dot files from <manifest>"
    echo "    -r <src> : Directory to fetch dot files from"
    echo "    -d <destination> : Target directory for dot files"
}

#
# Get to it!
#

# Gather arguments and such together.
while getopts "bcd:ehm:r:stvy" opt; do
    case $opt in
        b ) do_backup=0;;
        c ) do_copy=1;;
        e ) do_continue=1;;
        h ) do_help=1;;
        s ) do_silent=1;;
        t ) do_test=1;;
        v ) do_verbose=1;;
        y ) do_yes=1;;
        # Arguments
        d ) destination="${OPTARG}";;
        m ) manifest="${OPTARG}";;
        r ) src="${OPTARG}";;
        # If we got an invalid argument, show help text.
        * ) do_help=1;;
    esac
done

# Print help if requested, then exit.
if (( $do_help )); then
    help
    exit 0
fi

# Run the installation, then exit.
install_all
exit $?