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41ea61d59c
Some software decides based on uid/gid whether a user is a system or normal (human) user, with different behaviour for those flavors (example journald [2]). So adding logic to create system-users is necessary, we take the now common ranges from [1]. This extends the mkusers script to allow -2 for uid/gid, this argument will take an identifier from the user range. All identifiers used up to now should have been from the system range, so -1 is now interpreted as a system user/group. Note that after this commit, all the UIDs and GIDs that are created automatically (with -1) will change. That means if there is peristent data on an existing system that was created by such an automatic user, it will suddenly belong to a different user. However, this could already happen before: if a USERS line is added to a package, then other UIDs may change as well. Add system/user ranges as variables, and the argument for user/system uid variable as well. Thus some magic constants could be removed, some further occurences of -1 were replaced with equivalent logic. For consistency, the existing MIN/MAX_UID/GID variables are renamed to FIRST/LAST_USER_UID/GID. Update the documentation with the new automatic ranges. [1] - https://systemd.io/UIDS-GIDS/ [2] - https://www.freedesktop.org/software/systemd/man/journald.conf.html Signed-off-by: Norbert Lange <nolange79@gmail.com> [Arnout: use -1 for system users; refactor the changes a bit] Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>
472 lines
16 KiB
Bash
Executable File
472 lines
16 KiB
Bash
Executable File
#!/usr/bin/env bash
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set -e
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myname="${0##*/}"
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#----------------------------------------------------------------------------
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# Configurable items
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FIRST_USER_UID=1000
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LAST_USER_UID=1999
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FIRST_USER_GID=1000
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LAST_USER_GID=1999
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# use names from /etc/adduser.conf
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FIRST_SYSTEM_UID=100
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LAST_SYSTEM_UID=999
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FIRST_SYSTEM_GID=100
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LAST_SYSTEM_GID=999
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# argument to automatically crease system/user id
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AUTO_SYSTEM_ID=-1
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AUTO_USER_ID=-2
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# No more is configurable below this point
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#----------------------------------------------------------------------------
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#----------------------------------------------------------------------------
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error() {
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local fmt="${1}"
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shift
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printf "%s: " "${myname}" >&2
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printf "${fmt}" "${@}" >&2
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}
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fail() {
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error "$@"
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exit 1
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}
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#----------------------------------------------------------------------------
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if [ ${#} -ne 2 ]; then
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fail "usage: %s USERS_TABLE TARGET_DIR\n"
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fi
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USERS_TABLE="${1}"
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TARGET_DIR="${2}"
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shift 2
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PASSWD="${TARGET_DIR}/etc/passwd"
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SHADOW="${TARGET_DIR}/etc/shadow"
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GROUP="${TARGET_DIR}/etc/group"
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# /etc/gshadow is not part of the standard skeleton, so not everybody
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# will have it, but some may have it, and its content must be in sync
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# with /etc/group, so any use of gshadow must be conditional.
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GSHADOW="${TARGET_DIR}/etc/gshadow"
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# We can't simply source ${BR2_CONFIG} as it may contains constructs
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# such as:
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# BR2_DEFCONFIG="$(CONFIG_DIR)/defconfig"
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# which when sourced from a shell script will eventually try to execute
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# a command named 'CONFIG_DIR', which is plain wrong for virtually every
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# systems out there.
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# So, we have to scan that file instead. Sigh... :-(
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PASSWD_METHOD="$( sed -r -e '/^BR2_TARGET_GENERIC_PASSWD_METHOD="(.*)"$/!d;' \
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-e 's//\1/;' \
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"${BR2_CONFIG}" \
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)"
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#----------------------------------------------------------------------------
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get_uid() {
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local username="${1}"
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awk -F: -v username="${username}" \
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'$1 == username { printf( "%d\n", $3 ); }' "${PASSWD}"
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}
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#----------------------------------------------------------------------------
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get_ugid() {
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local username="${1}"
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awk -F: -v username="${username}" \
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'$1 == username { printf( "%d\n", $4 ); }' "${PASSWD}"
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}
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#----------------------------------------------------------------------------
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get_gid() {
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local group="${1}"
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awk -F: -v group="${group}" \
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'$1 == group { printf( "%d\n", $3 ); }' "${GROUP}"
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}
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#----------------------------------------------------------------------------
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get_members() {
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local group="${1}"
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awk -F: -v group="${group}" \
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'$1 == group { printf( "%s\n", $4 ); }' "${GROUP}"
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}
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#----------------------------------------------------------------------------
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get_username() {
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local uid="${1}"
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awk -F: -v uid="${uid}" \
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'$3 == uid { printf( "%s\n", $1 ); }' "${PASSWD}"
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}
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#----------------------------------------------------------------------------
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get_group() {
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local gid="${1}"
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awk -F: -v gid="${gid}" \
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'$3 == gid { printf( "%s\n", $1 ); }' "${GROUP}"
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}
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#----------------------------------------------------------------------------
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get_ugroup() {
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local username="${1}"
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local ugid
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ugid="$( get_ugid "${username}" )"
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if [ -n "${ugid}" ]; then
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get_group "${ugid}"
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fi
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}
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#----------------------------------------------------------------------------
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# Sanity-check the new user/group:
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# - check the gid is not already used for another group
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# - check the group does not already exist with another gid
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# - check the user does not already exist with another gid
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# - check the uid is not already used for another user
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# - check the user does not already exist with another uid
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# - check the user does not already exist in another group
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check_user_validity() {
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local username="${1}"
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local uid="${2}"
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local group="${3}"
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local gid="${4}"
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local _uid _ugid _gid _username _group _ugroup
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_group="$( get_group "${gid}" )"
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_gid="$( get_gid "${group}" )"
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_ugid="$( get_ugid "${username}" )"
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_username="$( get_username "${uid}" )"
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_uid="$( get_uid "${username}" )"
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_ugroup="$( get_ugroup "${username}" )"
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if [ "${username}" = "root" ]; then
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fail "invalid username '%s\n'" "${username}"
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fi
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if [ ${gid} -lt -2 -o ${gid} -eq 0 ]; then
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fail "invalid gid '%d' for '%s'\n" ${gid} "${username}"
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elif [ ${gid} -ge 0 ]; then
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# check the gid is not already used for another group
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if [ -n "${_group}" -a "${_group}" != "${group}" ]; then
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fail "gid '%d' for '%s' is already used by group '%s'\n" \
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${gid} "${username}" "${_group}"
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fi
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# check the group does not already exists with another gid
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# Need to split the check in two, otherwise '[' complains it
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# is missing arguments when _gid is empty
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if [ -n "${_gid}" ] && [ ${_gid} -ne ${gid} ]; then
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fail "group '%s' for '%s' already exists with gid '%d' (wants '%d')\n" \
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"${group}" "${username}" ${_gid} ${gid}
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fi
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# check the user does not already exists with another gid
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# Need to split the check in two, otherwise '[' complains it
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# is missing arguments when _ugid is empty
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if [ -n "${_ugid}" ] && [ ${_ugid} -ne ${gid} ]; then
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fail "user '%s' already exists with gid '%d' (wants '%d')\n" \
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"${username}" ${_ugid} ${gid}
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fi
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fi
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if [ ${uid} -lt -2 -o ${uid} -eq 0 ]; then
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fail "invalid uid '%d' for '%s'\n" ${uid} "${username}"
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elif [ ${uid} -ge 0 ]; then
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# check the uid is not already used for another user
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if [ -n "${_username}" -a "${_username}" != "${username}" ]; then
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fail "uid '%d' for '%s' already used by user '%s'\n" \
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${uid} "${username}" "${_username}"
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fi
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# check the user does not already exists with another uid
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# Need to split the check in two, otherwise '[' complains it
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# is missing arguments when _uid is empty
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if [ -n "${_uid}" ] && [ ${_uid} -ne ${uid} ]; then
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fail "user '%s' already exists with uid '%d' (wants '%d')\n" \
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"${username}" ${_uid} ${uid}
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fi
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fi
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# check the user does not already exist in another group
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if [ -n "${_ugroup}" -a "${_ugroup}" != "${group}" ]; then
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fail "user '%s' already exists with group '%s' (wants '%s')\n" \
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"${username}" "${_ugroup}" "${group}"
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fi
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return 0
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}
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#----------------------------------------------------------------------------
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# Generate a unique GID for given group. If the group already exists,
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# then simply report its current GID. Otherwise, generate the lowest GID
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# that is:
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# - not 0
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# - comprised in [$2..$3]
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# - not already used by a group
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generate_gid() {
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local group="${1}"
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local mingid="${2}"
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local maxgid="${3}"
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local gid
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gid="$( get_gid "${group}" )"
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if [ -z "${gid}" ]; then
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for(( gid=mingid; gid<=maxgid; gid++ )); do
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if [ -z "$( get_group "${gid}" )" ]; then
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break
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fi
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done
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if [ ${gid} -gt ${maxgid} ]; then
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fail "can not allocate a GID for group '%s'\n" "${group}"
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fi
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fi
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printf "%d\n" "${gid}"
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}
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#----------------------------------------------------------------------------
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# Add a group; if it does already exist, remove it first
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add_one_group() {
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local group="${1}"
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local gid="${2}"
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local members
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# Generate a new GID if needed
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if [ ${gid} -eq ${AUTO_USER_ID} ]; then
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gid="$( generate_gid "${group}" $FIRST_USER_GID $LAST_USER_GID )"
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elif [ ${gid} -eq ${AUTO_SYSTEM_ID} ]; then
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gid="$( generate_gid "${group}" $FIRST_SYSTEM_GID $LAST_SYSTEM_GID )"
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fi
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members=$(get_members "$group")
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# Remove any previous instance of this group, and re-add the new one
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sed -i --follow-symlinks -e '/^'"${group}"':.*/d;' "${GROUP}"
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printf "%s:x:%d:%s\n" "${group}" "${gid}" "${members}" >>"${GROUP}"
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# Ditto for /etc/gshadow if it exists
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if [ -f "${GSHADOW}" ]; then
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sed -i --follow-symlinks -e '/^'"${group}"':.*/d;' "${GSHADOW}"
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printf "%s:*::\n" "${group}" >>"${GSHADOW}"
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fi
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}
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#----------------------------------------------------------------------------
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# Generate a unique UID for given username. If the username already exists,
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# then simply report its current UID. Otherwise, generate the lowest UID
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# that is:
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# - not 0
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# - comprised in [$2..$3]
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# - not already used by a user
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generate_uid() {
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local username="${1}"
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local minuid="${2}"
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local maxuid="${3}"
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local uid
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uid="$( get_uid "${username}" )"
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if [ -z "${uid}" ]; then
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for(( uid=minuid; uid<=maxuid; uid++ )); do
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if [ -z "$( get_username "${uid}" )" ]; then
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break
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fi
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done
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if [ ${uid} -gt ${maxuid} ]; then
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fail "can not allocate a UID for user '%s'\n" "${username}"
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fi
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fi
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printf "%d\n" "${uid}"
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}
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#----------------------------------------------------------------------------
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# Add given user to given group, if not already the case
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add_user_to_group() {
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local username="${1}"
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local group="${2}"
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local _f
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for _f in "${GROUP}" "${GSHADOW}"; do
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[ -f "${_f}" ] || continue
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sed -r -i --follow-symlinks \
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-e 's/^('"${group}"':.*:)(([^:]+,)?)'"${username}"'(,[^:]+*)?$/\1\2\4/;' \
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-e 's/^('"${group}"':.*)$/\1,'"${username}"'/;' \
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-e 's/,+/,/' \
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-e 's/:,/:/' \
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"${_f}"
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done
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}
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#----------------------------------------------------------------------------
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# Encode a password
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encode_password() {
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local passwd="${1}"
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mkpasswd -m "${PASSWD_METHOD}" "${passwd}"
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}
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#----------------------------------------------------------------------------
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# Add a user; if it does already exist, remove it first
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add_one_user() {
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local username="${1}"
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local uid="${2}"
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local group="${3}"
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local gid="${4}"
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local passwd="${5}"
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local home="${6}"
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local shell="${7}"
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local groups="${8}"
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local comment="${9}"
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local _f _group _home _shell _gid _passwd
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# First, sanity-check the user
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check_user_validity "${username}" "${uid}" "${group}" "${gid}"
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# Generate a new UID if needed
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if [ ${uid} -eq ${AUTO_USER_ID} ]; then
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uid="$( generate_uid "${username}" $FIRST_USER_GID $LAST_USER_GID )"
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elif [ ${uid} -eq ${AUTO_SYSTEM_ID} ]; then
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uid="$( generate_uid "${username}" $FIRST_SYSTEM_GID $LAST_SYSTEM_GID )"
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fi
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# Remove any previous instance of this user
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for _f in "${PASSWD}" "${SHADOW}"; do
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sed -r -i --follow-symlinks -e '/^'"${username}"':.*/d;' "${_f}"
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done
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_gid="$( get_gid "${group}" )"
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_shell="${shell}"
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if [ "${shell}" = "-" ]; then
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_shell="/bin/false"
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fi
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case "${home}" in
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-) _home="/";;
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/) fail "home can not explicitly be '/'\n";;
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/*) _home="${home}";;
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*) fail "home must be an absolute path\n";;
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esac
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case "${passwd}" in
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-)
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_passwd=""
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;;
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!=*)
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_passwd='!'"$( encode_password "${passwd#!=}" )"
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;;
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=*)
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_passwd="$( encode_password "${passwd#=}" )"
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;;
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*)
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_passwd="${passwd}"
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;;
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esac
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printf "%s:x:%d:%d:%s:%s:%s\n" \
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"${username}" "${uid}" "${_gid}" \
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"${comment}" "${_home}" "${_shell}" \
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>>"${PASSWD}"
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printf "%s:%s:::::::\n" \
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"${username}" "${_passwd}" \
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>>"${SHADOW}"
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# Add the user to its additional groups
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if [ "${groups}" != "-" ]; then
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for _group in ${groups//,/ }; do
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add_user_to_group "${username}" "${_group}"
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done
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fi
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# If the user has a home, chown it
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# (Note: stdout goes to the fakeroot-script)
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if [ "${home}" != "-" ]; then
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mkdir -p "${TARGET_DIR}/${home}"
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printf "chown -h -R %d:%d '%s'\n" "${uid}" "${_gid}" "${TARGET_DIR}/${home}"
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fi
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}
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#----------------------------------------------------------------------------
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main() {
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local username uid group gid passwd home shell groups comment
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local line
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local auto_id
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local -a ENTRIES
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# Some sanity checks
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if [ ${FIRST_USER_UID} -le 0 ]; then
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fail "FIRST_USER_UID must be >0 (currently %d)\n" ${FIRST_USER_UID}
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fi
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if [ ${FIRST_USER_GID} -le 0 ]; then
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fail "FIRST_USER_GID must be >0 (currently %d)\n" ${FIRST_USER_GID}
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fi
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# Read in all the file in memory, exclude empty lines and comments
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while read line; do
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ENTRIES+=( "${line}" )
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done < <( sed -r -e 's/#.*//; /^[[:space:]]*$/d;' "${USERS_TABLE}" )
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# We first create groups whose gid is positive, and then we create groups
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# whose gid is automatic, so that, if a group is defined both with
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# a specified gid and an automatic gid, we ensure the specified gid is
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# used, rather than a different automatic gid is computed.
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# First, create all the main groups which gid is *not* automatic
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for line in "${ENTRIES[@]}"; do
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read username uid group gid passwd home shell groups comment <<<"${line}"
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[ ${gid} -ge 0 ] || continue # Automatic gid
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add_one_group "${group}" "${gid}"
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done
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# Then, create all the main groups which gid *is* automatic
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for line in "${ENTRIES[@]}"; do
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read username uid group gid passwd home shell groups comment <<<"${line}"
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[ ${gid} -lt 0 ] || continue # Non-automatic gid
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add_one_group "${group}" "${gid}"
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done
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# Then, create all the additional groups
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# If any additional group is already a main group, we should use
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# the gid of that main group; otherwise, we can use any gid - a
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# system gid if the uid is a system user (<= LAST_SYSTEM_UID),
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# otherwise a user gid.
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for line in "${ENTRIES[@]}"; do
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read username uid group gid passwd home shell groups comment <<<"${line}"
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if [ "${groups}" != "-" ]; then
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if [ ${uid} -le 0 ]; then
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auto_id=${uid}
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elif [ ${uid} -le ${LAST_SYSTEM_UID} ]; then
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auto_id=${AUTO_SYSTEM_ID}
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else
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auto_id=${AUTO_USER_ID}
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fi
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for g in ${groups//,/ }; do
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add_one_group "${g}" ${auto_id}
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done
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fi
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done
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# When adding users, we do as for groups, in case two packages create
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# the same user, one with an automatic uid, the other with a specified
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# uid, to ensure the specified uid is used, rather than an incompatible
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# uid be generated.
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# Now, add users whose uid is *not* automatic
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for line in "${ENTRIES[@]}"; do
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read username uid group gid passwd home shell groups comment <<<"${line}"
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[ "${username}" != "-" ] || continue # Magic string to skip user creation
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[ ${uid} -ge 0 ] || continue # Automatic uid
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add_one_user "${username}" "${uid}" "${group}" "${gid}" "${passwd}" \
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"${home}" "${shell}" "${groups}" "${comment}"
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done
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# Finally, add users whose uid *is* automatic
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for line in "${ENTRIES[@]}"; do
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read username uid group gid passwd home shell groups comment <<<"${line}"
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[ "${username}" != "-" ] || continue # Magic string to skip user creation
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[ ${uid} -lt 0 ] || continue # Non-automatic uid
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add_one_user "${username}" "${uid}" "${group}" "${gid}" "${passwd}" \
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"${home}" "${shell}" "${groups}" "${comment}"
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done
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}
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#----------------------------------------------------------------------------
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main "${@}"
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