+#!/bin/bash
+
+# a set of useful functions for managing operations with passwords.
+# a set of very simple operations, but the file needs to be protected from
+# undesirable access. a good way to do that is to make the file owned by
+# root, and for it to have permssions of "600" (full access by owner only),
+# and to only try to read the password file when in sudo mode. the first
+# two requirements are done automatically by the store_password function.
+
+# load_password:
+# provides a way to read a password out of a file.
+# the return value is an echoed password, so this method should always be
+# called from within a subshell, e.g.:
+# mypass="$(load_password /etc/glorp/secret_passcode)"
+# the returned echo will be blank if the function failed.
+function load_password()
+{
+ local passfile="$1"; shift
+ if [ -z "$passfile" ]; then
+ echo 'The load_password function needs a filename to read the password from.'
+ return 1
+ fi
+ local passwd
+ read passwd < "$passfile"
+ echo "$passwd"
+}
+
+# stores a password into a password file. the password file should be the
+# first parameter and the password should be the second.
+# this makes sure that only root can read the file.
+function store_password()
+{
+ local passfile="$1"; shift
+ local passwd="$1"; shift
+ if [ -z "$passfile" -o -z "$passwd" ]; then
+ echo '
+The store_password function needs (1) the file to store the password into,
+and (2) the password that should be stored.
+'
+ return 1
+ fi
+
+ echo "$passwd" > "$passfile"
+ test_or_die "writing password into the file $passfile"
+
+ chown root:root "$passfile"
+ test_or_die "chowning the password file to root ownership for: $passfile"
+
+ chmod 600 "$passfile"
+ test_or_die "restricting permissions on password file for: $passfile"
+}
+
+# reads a password from the console, without echoing the letters when they
+# are typed. the prompt to show the user is required as the first parameter.
+# the password read in is returned as an echo, like load_password above.
+function read_password()
+{
+ prompt="$1"; shift
+ echo -n "$prompt "
+ # turn off echo but remember former setting.
+ stty_orig=`stty -g`
+ stty -echo
+ read the_passwd
+ # turn echo back on.
+ stty $stty_orig
+ # return the password as an echo.
+ echo "$the_passwd"
+}
+
+