doc

#!/bin/bash
#
# Show Debian changelog and other package documents.
#
# VERSION       :0.1.1
# DATE          :2016-12-13
# URL           :https://github.com/szepeviktor/debian-server-tools
# AUTHOR        :Viktor Szépe <viktor@szepe.net>
# LICENSE       :The MIT License (MIT)
# BASH-VERSION  :4.2+
# LOCATION      :/usr/local/bin/doc

set -e

declare OPT
declare SUFFIX
declare PKG
declare FILENAME="changelog"
declare DEBIAN=".Debian"

while getopts :urnh OPT; do
    case "$OPT" in
        u)
            DEBIAN=""
            ;;
        r)
            FILENAME="README"
            ;;
        n)
            FILENAME="NEWS"
            ;;
        # You may add other files here like TODO or copyright
        h)
            cat <<"EOF"
Usage: doc [OPTION]... [PACKAGE]
Display package documentation for a Debian package.

doc package       Show Debian changelog
doc -u package    Show upstream changelog
doc -r package    Show Debian readme
doc -ur package   Show upstream readme
doc -n package    Show Debian news
doc -un package   Show upstream news
doc -h            Display this help and exit
EOF
            exit 0
            ;;
        ?)
            echo "Invalid option (${OPT})" 1>&2
            exit 2
            ;;
    esac
done

shift "$((OPTIND - 1))"

# Incorrect number of arguments
test $# -eq 1

# Last option must be the package name
PKG="$1"

# Incorrect package name
test -n "$PKG"

# Check documentation exists for the package
test -d "/usr/share/doc/${PKG}"

# changelog.gz or changelog or changelog.md.gz or changelog.md
for SUFFIX in .gz "" .md.gz .md; do
    if [ -f "/usr/share/doc/${PKG}/${FILENAME}${DEBIAN}${SUFFIX}" ]; then
        # File is found, show its content in the default pager
        if [ "${SUFFIX%.gz}" != "$SUFFIX" ]; then
            zcat "/usr/share/doc/${PKG}/${FILENAME}${DEBIAN}${SUFFIX}" | pager
        else
            pager "/usr/share/doc/${PKG}/${FILENAME}${DEBIAN}${SUFFIX}"
        fi
        exit 0
    fi
done

echo "File not found /usr/share/doc/${PKG}/${FILENAME}${DEBIAN}[.md][.gz]" 1>&2
exit 3