1 | #!/usr/bin/perl -w |
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2 | # |
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3 | # A script to change the IP/hostname on a cluster machine |
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4 | # jdreed@mit.edu |
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5 | |
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6 | use strict; |
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7 | use Socket; |
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8 | use File::Copy; |
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9 | use Getopt::Std; |
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10 | |
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11 | # sulogin gets upset if it gets a ^C |
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12 | $SIG{'INT'} = 'bail'; |
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13 | |
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14 | my $MASKS="/usr/share/debathena-recovery-mode-config/masks"; |
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15 | |
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16 | if (defined($ARGV[0]) && ($ARGV[0] eq 'test')) { |
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17 | print "Change IP address or hostname\n"; |
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18 | exit 0; |
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19 | } |
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20 | |
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21 | sub confirm { |
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22 | my $question = shift || "Continue?"; |
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23 | print "${question} (y/n) "; |
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24 | my $ans = <STDIN>; |
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25 | return ($ans =~ m/^y$/i); |
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26 | } |
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27 | |
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28 | sub bail { |
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29 | if ($_[0] eq 'INT') { |
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30 | print "\nCancelled."; |
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31 | } else { |
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32 | print shift; |
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33 | } |
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34 | print "\n\n(press ENTER to return to the recovery mode menu)\n"; |
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35 | my $dummy = <STDIN>; |
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36 | exit 0; |
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37 | } |
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38 | |
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39 | sub mask { |
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40 | my $ip = shift; |
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41 | my $mask = shift; |
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42 | my $mbits = pack("B*", (1 x $mask) . (0 x (32 - $mask))); |
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43 | my $ibits = pack("CCCC", split(/\./, $ip)); |
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44 | my $net = $ibits & $mbits; |
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45 | return join('.', unpack("CCCC", $net)); |
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46 | } |
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47 | |
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48 | sub cidr2ip { |
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49 | my $cidr = shift; |
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50 | return join('.', unpack("CCCC", pack("B*", (1 x $cidr) . (0 x (32 - $cidr))))); |
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51 | } |
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52 | |
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53 | sub validIP { |
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54 | my $ip = shift; |
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55 | if ($ip =~ /^(\d{1,3})\.(\d{1,3})\.(\d{1,3})\.(\d{1,3})$/) { |
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56 | if (scalar(grep { ($_ <= 255) && ($_ >= 0) } ($1, $2, $3, $4)) == 4) { |
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57 | return 1; |
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58 | } |
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59 | } |
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60 | return 0; |
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61 | } |
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62 | |
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63 | # main |
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64 | |
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65 | # Sanity checks |
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66 | foreach (qw(/etc/network/interfaces /etc/hosts /etc/hostname)) { |
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67 | (-w $_) || bail("Cannot write to $_. (Are you root?)"); |
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68 | } |
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69 | |
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70 | (-r $MASKS) || bail("Cannot read $MASKS"); |
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71 | |
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72 | my $machtype = `machtype -L`; |
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73 | chomp($machtype); |
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74 | if ($machtype ne 'debathena-cluster') { |
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75 | print "WARNING: This script is designed for debathena-cluster machines but\n"; |
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76 | print "this machine is running $machtype.\n"; |
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77 | confirm("Are you SURE you want to continue?") || bail("OK, cancelled."); |
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78 | } |
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79 | |
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80 | my $ip = ''; |
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81 | until (validIP($ip)) { |
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82 | if ($ip) { |
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83 | print "Invalid IP address ($ip). Try again.\n"; |
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84 | } |
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85 | print "Enter the new IP address: "; |
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86 | ($ip = <STDIN>) =~ s/\s//g; |
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87 | } |
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88 | print "Looking up hostname..."; |
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89 | my $fqdn = gethostbyaddr(inet_aton($ip), AF_INET); |
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90 | if ($fqdn) { |
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91 | print " found.\n"; |
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92 | } else { |
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93 | $fqdn = ''; |
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94 | print " not found.\n"; |
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95 | until ($fqdn =~ /^[a-z][\w\-\.]*/i) { |
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96 | print "Please enter the machine's new hostname: "; |
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97 | ($fqdn = <STDIN>) =~ s/\s//g; |
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98 | } |
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99 | } |
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100 | $fqdn = lc($fqdn); |
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101 | my $hostname = $fqdn; |
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102 | if ($fqdn =~ /\./) { |
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103 | $hostname = (split(/\./, $fqdn))[0]; |
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104 | } else { |
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105 | print "NOTE: No domain specified, assuming 'mit.edu'"; |
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106 | $fqdn = "${hostname}.mit.edu"; |
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107 | } |
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108 | |
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109 | my ($subnetmask, $gateway); |
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110 | print "Looking up netmask information...\n"; |
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111 | open(MASKS, $MASKS) || bail("Cannot read $MASKS: $!"); |
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112 | while (<MASKS>) { |
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113 | next if (/^#/); |
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114 | next unless (/\d/); |
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115 | my ($addr, $sbits, $mbits, $gw) = split(' '); #the ' ' pattern emulates awk |
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116 | if (mask($ip, $sbits) eq $addr) { |
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117 | $subnetmask = cidr2ip($mbits); |
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118 | if (! $gw) { |
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119 | my @octets = split(/\./, mask($ip, $mbits)); |
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120 | my $trailing = pop(@octets) + 1; |
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121 | $gateway = join('.', @octets, $trailing); |
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122 | } else { |
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123 | $gateway = $gw; |
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124 | } |
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125 | last; |
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126 | } |
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127 | } |
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128 | (defined($subnetmask) && defined($gateway)) || bail("Could not find a matching line in masks file for $ip.\nIf you are sure you typed the IP address correctly, please report\nthis error to IS&T, along with the IP address you were trying to use."); |
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129 | |
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130 | close(MASKS); |
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131 | print "IP address: $ip\n"; |
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132 | print "Subnet Mask: $subnetmask\n"; |
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133 | print "Gateway: $gateway\n"; |
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134 | print "Hostname: $hostname\n"; |
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135 | print "FQDN: $fqdn\n\n"; |
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136 | |
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137 | confirm("Does that look correct?") || bail("OK, cancelled."); |
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138 | |
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139 | print "Updating /etc/network/interfaces...\n"; |
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140 | copy("/etc/network/interfaces", "/etc/network/interfaces.old") || bail("Could not copy /etc/network/interfaces"); |
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141 | open(INTERFACES, ">/etc/network/interfaces") || bail ("Could not overwrite /etc/network/interfaces: $!"); |
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142 | print INTERFACES <<"ENDINTERFACES"; |
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143 | # This file was created by $0 |
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144 | |
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145 | # The loopback interface |
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146 | auto lo |
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147 | iface lo inet loopback |
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148 | |
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149 | # The primary network interface |
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150 | auto eth0 |
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151 | iface eth0 inet static |
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152 | address $ip |
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153 | netmask $subnetmask |
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154 | gateway $gateway |
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155 | dns-nameservers 18.70.0.160 18.71.0.151 18.72.0.3 |
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156 | ENDINTERFACES |
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157 | close(INTERFACES); |
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158 | |
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159 | print "Updating /etc/hosts...\n"; |
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160 | |
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161 | copy("/etc/hosts", "/etc/hosts.old") || bail("Could not copy /etc/hosts"); |
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162 | open(HOSTS, ">/etc/hosts") || bail ("Could not overwrite /etc/hosts: $!"); |
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163 | print HOSTS <<"ENDHOSTS"; |
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164 | # This file was created by $0 |
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165 | 127.0.0.1 localhost |
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166 | 127.0.1.1 $fqdn $hostname |
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167 | |
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168 | # The following lines are desirable for IPv6 capable hosts |
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169 | ::1 localhost ip6-localhost ip6-loopback |
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170 | fe00::0 ip6-localnet |
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171 | ff00::0 ip6-mcastprefix |
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172 | ff02::1 ip6-allnodes |
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173 | ff02::2 ip6-allrouters |
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174 | ff02::3 ip6-allhosts |
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175 | ENDHOSTS |
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176 | close(HOSTS); |
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177 | |
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178 | print "Updating /etc/hostname...\n"; |
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179 | copy("/etc/hostname", "/etc/hostname.old") || bail("Could not copy /etc/hostname"); |
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180 | open(HOSTNAME, ">/etc/hostname") || bail ("Could not overwrite /etc/hostname: $!"); |
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181 | print HOSTNAME "$hostname\n"; |
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182 | close(HOSTNAME); |
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183 | |
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184 | print "Setting hostname...\n"; |
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185 | system("/bin/hostname", $hostname); |
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186 | print "\nDone! You will need to reboot the workstation for the\n"; |
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187 | print "changes to take effect.\n"; |
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188 | confirm("Would you like to reboot now?") || bail("Please perform a full shutdown and reboot as soon as possible."); |
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189 | print "The workstation will now power down completely.\n"; |
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190 | print "When you turn it back on, it will use the new IP address.\n\n"; |
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191 | print "(press ENTER to power down the workstation)"; |
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192 | getc(STDIN); |
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193 | system("/sbin/poweroff"); |
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194 | exit 0; |
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