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✏️ Editing: system-setup

#!/bin/bash

# system-setup has been split into scripts under /etc/scripts/system-setup.d
# the purpose is to have different skel areas contribute different scripts into
# the system-setup stage

# Set null globbing, we need this for our scripts (cf. usr/sbin/rear).
# With nullglob set when e.g. for foo*bar no file matches are found, then foo*bar is removed
# (e.g. "ls foo*bar" becomes plain "ls" without "foo*bar: No such file or directory" error).
shopt -s nullglob

# Use an artificial array to get the kernel command line parameters as array elements
kernel_command_line=( $( cat /proc/cmdline ) )

function rear_debug() {
    for kernel_command_line_parameter in "${kernel_command_line[@]}" ; do
        test "debug" = "$kernel_command_line_parameter" && return 0
    done
    return 1
}

function unattended_recovery() {
    for kernel_command_line_parameter in "${kernel_command_line[@]}" ; do
        test "unattended" = "$kernel_command_line_parameter" && return 0
    done
    return 1
}

function automatic_recovery() {
    # The unattended recovery mode implies automatic recovery (see the implementations below)
    # so that in unattended mode the automatic recovery code below must not be run
    # otherwise first the automatic recovery code and then the unattended recovery code
    # get run automatically one after the other where the unattended recovery fails
    # because for two subsequent 'rear recover' the second one fails:
    unattended_recovery && return 1
    for kernel_command_line_parameter in "${kernel_command_line[@]}" ; do
        test "auto_recover" = "$kernel_command_line_parameter" && return 0
        test "automatic" = "$kernel_command_line_parameter" && return 0
    done
    return 1
}

# The 'sleep 1' is used as workaround to avoid whatever inexplicable actual reason
# that at least on SLES12 some initial output lines of this script would get lost
# (perhaps somewhere in systemd's nowhere land) which results that in partricular
# in Relax-and-Recover debug mode the user sits in front of an empty screen wondering
# why nothing happens because in partricular the read prompt "Press ENTER ..." was lost,
# cf. the 'if rear_debug' part below:
sleep 1

if rear_debug ; then
    echo -e "\nIn Relax-and-Recover debug mode a shell will be started by default on tty9\n"
    read -n 1 -p "Press ENTER or type a digit '2...8' for another tty or '0' to skip it "
    case "$REPLY" in
        (0)
            echo -e "\nNo debug mode shell started\n"
            ;;
        ([2-8])
            /bin/bash </dev/tty$REPLY >/dev/tty$REPLY 2>&1 &
            echo -e "\nStarted debug mode shell on tty$REPLY\n"
            ;;
        (*)
            /bin/bash </dev/tty9 >/dev/tty9 2>&1 &
            echo -e "\nStarted debug mode shell on tty9\n"
            ;;
    esac
fi

# Sourcing of the conf/default.conf file as we may use some defined variables or arrays
# E.g. UDEV_NET_MAC_RULE_FILES is used by script 55-migrate-network-devices.sh
test -f /usr/share/rear/conf/default.conf && source /usr/share/rear/conf/default.conf
# Sourcing user and rescue configuration as we need some variables
# (EXCLUDE_MD5SUM_VERIFICATION right now and other variables in the system setup scripts):
# The order of sourcing should be 'site' then 'local' and as last 'rescue'
for conf in site local rescue ; do
    test -f /etc/rear/$conf.conf && source /etc/rear/$conf.conf
done

# Verifying md5sums must happen first of all during recovery system startup
# before files may get changed by the recovery system startup scripts below
# otherwise one may get false positives like
#   ./var/log/lastlog: FAILED
#   ./etc/resolv.conf: FAILED
#   ./etc/udev/rules.d/70-persistent-net.rules: FAILED
#   ./etc/inittab: FAILED
#   ./etc/issue: FAILED
# The /md5sums.txt file would be empty if the md5sums were not successfully created
# during "rear mkrescue/mkbackup" by the build/default/995_md5sums_rootfs.sh script:
if test -s "/md5sums.txt" ; then
    echo -e "\nVerifying md5sums of the files in the Relax-and-Recover rescue system\n"
    # /etc/issue is always excluded to avoid that verifying its md5sum fails with "./etc/issue: FAILED"
    # when there is no rsa SSH host key /etc/ssh/ssh_host_rsa_key in the recovery system
    # because then /etc/scripts/run-sshd creates one and adds its SSH fingerprint to /etc/issue
    # and /etc/scripts/run-sshd is run by SysVinit or systemd
    # (via /etc/inittab and /etc/init/start-sshd.conf or /usr/lib/systemd/system/sshd.service)
    # so that /etc/issue may get modified before its md5sum is verified here.
    # run-sshd also modifies /etc/ssh/sshd_config, so this is excluded as well.
    # Also /etc/udev/rules.d/70-persistent-net.rules is always excluded to avoid false alarm
    # because it seems it can be modified even before this md5sum verification here runs,
    # see https://github.com/rear/rear/issues/1883#issuecomment-409875733
    egrep_pattern="/etc/issue|/etc/ssh/sshd_config|/etc/udev/rules.d/70-persistent-net.rules"
    test "$EXCLUDE_MD5SUM_VERIFICATION" && egrep_pattern="$egrep_pattern|$EXCLUDE_MD5SUM_VERIFICATION"
    # Regardless of '--quiet' md5sum shows "FAILED" messages nevertheless (cf. 'man md5sum'):
    if grep -E -v "$egrep_pattern" md5sums.txt | md5sum --quiet --check ; then
        echo -e "md5sums are OK\n"
    else
        # In case of a FAILED md5sum inform the user:
        echo "Possibly corrupted Relax-and-Recover rescue system"
        if rear_debug ; then
            # In debug mode let the user confirm to proceed:
            read -p "Press ENTER to proceed 'bona fide' nevertheless "
        else
            # In non-debug mode wait 10 seconds so that the user can read the md5sum output:
            echo -e "Proceeding 'bona fide' nevertheless...\n"
            sleep 10
        fi
    fi
fi

echo -e "\nConfiguring Relax-and-Recover rescue system\n"
for system_setup_script in /etc/scripts/system-setup.d/*.sh ; do
    if rear_debug ; then
        read -p "Press ENTER to run $( basename $system_setup_script ) "
        set -x
        source $system_setup_script
        # The only known way how to do 'set +x' after 'set -x' without a '+ set +x' output:
        { set +x ; } 2>/dev/null
        echo
    else
        echo "Running $( basename $system_setup_script )..."
        source $system_setup_script
    fi
done
echo -e "\nRelax-and-Recover rescue system is ready\n"
# Wait two seconds so that the user can read the 'Relax-and-Recover rescue system is ready' message
# on his screen before the screen gets cleared and replaced by the login screen:
sleep 2

# In debug mode run the automated 'rear recover' also with debug options.
# Because the kernel command line option 'debug' means 'set -x' for the system setup scripts
# it also means '-D' (i.e. 'set -x') for the automated 'rear recover' run:
if rear_debug ; then
    rear_debug_options='-D'
else
    rear_debug_options=''
fi

# Launch rear recover automatically:
if automatic_recovery ; then
    choices=( "View Relax-and-Recover log file(s)"
              "Go to Relax-and-Recover shell"
            )
    echo -e "\nLaunching 'rear recover' automatically\n"
    # The recover workflow is always verbose (see usr/sbin/rear):
    if rear $rear_debug_options recover ; then
        echo -e "\n'rear recover' finished successfully\n"
        choices+=( "Reboot" )
    else
        echo -e "\n'rear recover' failed, check the Relax-and-Recover log file(s)\n"
    fi
    PS3="Select what to do "
    select choice in "${choices[@]}" ; do
        case "$REPLY" in
            (1)
                # Do not assume the ReaR log file is named rear-$HOSTNAME.log
                # the user can have specified any name as LOGFILE:
                less /var/log/rear/*
                ;;
            (2)
                echo "" > /etc/issue
                echo "" > /etc/motd
                break
                ;;
            (3)
                reboot
                ;;
        esac
        for (( i=1 ; i <= ${#choices[@]} ; i++ )) ; do
            echo "$i) ${choices[$i-1]}"
        done
    done 2>&1
fi

# Launch rear recover automatically in unattended mode
# i.e. with automated reboot after successful 'rear recover':
if unattended_recovery ; then
    choices=( "View Relax-and-Recover log file(s)"
              "Go to Relax-and-Recover shell"
            )
    echo -e "\nLaunching 'rear recover' automatically in unattended mode\n"
    # The recover workflow is always verbose (see usr/sbin/rear):
    if rear $rear_debug_options recover ; then
        echo -e "\n'rear recover' finished successfully\n"
        echo -e "\nRebooting in 30 seconds (Ctrl-C to interrupt)\n"
        sleep 30
        reboot
    else
        echo -e "\n'rear recover' failed, check the Relax-and-Recover log file(s)\n"
        PS3="Select what to do "
        select choice in "${choices[@]}" ; do
            case "$REPLY" in
                (1)
                    # Do not assume the ReaR log file is named rear-$HOSTNAME.log
                    # the user can have specified any name as LOGFILE:
                    less /var/log/rear/*
                    ;;
                (2)
                    echo "" > /etc/issue
                    echo "" > /etc/motd
                    break
                    ;;
            esac
            for (( i=1 ; i <= ${#choices[@]} ; i++ )) ; do
                echo "$i) ${choices[$i-1]}"
            done
        done 2>&1
    fi
fi

MR SKB