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1 .\" -*- nroff -*-
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2 .rn '' }`
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3 '\" $Header$
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4 '\"
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5 '\" $Log$
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6 '\" Revision 1.1 2005/04/18 14:46:05 kono
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7 '\" Initial revision
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8 '\"
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9 '\" Revision 2.0.1.2 88/06/22 20:47:18 lwall
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10 '\" patch12: now avoids Bell System Logo
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11 '\"
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12 '\" Revision 2.0.1.1 88/06/03 15:12:51 lwall
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13 '\" patch10: -B switch was contributed.
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14 '\"
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15 '\" Revision 2.0 86/09/17 15:39:09 lwall
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16 '\" Baseline for netwide release.
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17 '\"
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18 '\" Revision 1.4 86/08/01 19:23:22 lwall
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19 '\" Documented -v, -p, -F.
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20 '\" Added notes to patch senders.
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21 '\"
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22 '\" Revision 1.3 85/03/26 15:11:06 lwall
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23 '\" Frozen.
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24 '\"
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25 '\" Revision 1.2.1.4 85/03/12 16:14:27 lwall
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26 '\" Documented -p.
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27 '\"
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28 '\" Revision 1.2.1.3 85/03/12 16:09:41 lwall
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29 '\" Documented -D.
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30 '\"
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31 '\" Revision 1.2.1.2 84/12/05 11:06:55 lwall
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32 '\" Added -l switch, and noted bistability bug.
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33 '\"
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34 '\" Revision 1.2.1.1 84/12/04 17:23:39 lwall
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35 '\" Branch for sdcrdcf changes.
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36 '\"
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37 '\" Revision 1.2 84/12/04 17:22:02 lwall
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38 '\" Baseline version.
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39 '\"
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40 .de Sh
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41 .br
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42 .ne 5
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43 .PP
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44 \fB\\$1\fR
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45 .PP
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46 ..
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47 .de Sp
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48 .if t .sp .5v
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49 .if n .sp
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50 ..
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51 '\"
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52 '\" Set up \*(-- to give an unbreakable dash;
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53 '\" string Tr holds user defined translation string.
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54 '\" Bell System Logo is used as a dummy character.
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55 '\"
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56 '\" Shut up a groff -ww warning.
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57 .if \n(.g .if !dTr .ds Tr
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58 .ie n \{\
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59 .tr \(*W-\*(Tr
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60 .ds -- \(*W-
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61 .if (\n(.H=4u)&(1m=24u) .ds -- \(*W\h'-12u'\(*W\h'-12u'-\" diablo 10 pitch
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62 .if (\n(.H=4u)&(1m=20u) .ds -- \(*W\h'-12u'\(*W\h'-8u'-\" diablo 12 pitch
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63 .ds L" ""
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67 'br \}
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68 .el \{\
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70 .tr \*(Tr
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73 .ds L' `
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74 .ds R' '
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75 'br\}
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76 .TH PATCH 1 LOCAL
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77 .SH NAME
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78 patch - apply a diff file to an original
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79 .SH SYNOPSIS
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80 .B patch
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81 [options] [origfile [patchfile]] [+ [options] [origfile]]...
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82 .sp
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83 but usually just
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84 .sp
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85 .B patch
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86 <patchfile
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87 .SH DESCRIPTION
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88 .I Patch
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89 will take a patch file containing any of the four forms of difference
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90 listing produced by the
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91 .I diff
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92 program and apply those differences to an original file, producing a patched
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93 version.
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94 By default, the patched version is put in place of the original, with
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95 the original file backed up to the same name with the
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96 extension \*(L".orig\*(R" (\*(L"~\*(R" on systems that do not
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97 support long filenames), or as specified by the
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98 .BR -b ,
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99 .BR -B ,
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100 or
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101 .B -V
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102 switches.
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103 The extension used for making backup files may also be specified in the
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104 .B SIMPLE_BACKUP_SUFFIX
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105 environment variable, which is overridden by above switches.
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106 .PP
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107 If the backup file already exists,
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108 .B patch
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109 creates a new backup file name by changing the first lowercase letter
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110 in the last component of the file's name into uppercase. If there are
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111 no more lowercase letters in the name, it removes the first character
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112 from the name. It repeats this process until it comes up with a
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113 backup file that does not already exist.
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114 .PP
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115 You may also specify where you want the output to go with a
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116 .B -o
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117 switch; if that file already exists, it is backed up first.
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118 .PP
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119 If
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120 .I patchfile
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121 is omitted, or is a hyphen, the patch will be read from standard input.
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122 .PP
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123 Upon startup, patch will attempt to determine the type of the diff listing,
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124 unless over-ruled by a
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125 .BR -c ,
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126 .BR -e ,
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127 .BR -n ,
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128 or
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129 .B -u
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130 switch.
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131 Context diffs (old-style, new-style, and unified) and
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132 normal diffs are applied by the
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133 .I patch
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134 program itself, while ed diffs are simply fed to the
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135 .I ed
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136 editor via a pipe.
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137 .PP
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138 .I Patch
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139 will try to skip any leading garbage, apply the diff,
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140 and then skip any trailing garbage.
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141 Thus you could feed an article or message containing a
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142 diff listing to
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143 .IR patch ,
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144 and it should work.
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145 If the entire diff is indented by a consistent amount,
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146 this will be taken into account.
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147 .PP
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148 With context diffs, and to a lesser extent with normal diffs,
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149 .I patch
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150 can detect when the line numbers mentioned in the patch are incorrect,
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151 and will attempt to find the correct place to apply each hunk of the patch.
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152 As a first guess, it takes the line number mentioned for the hunk, plus or
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153 minus any offset used in applying the previous hunk.
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154 If that is not the correct place,
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155 .I patch
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156 will scan both forwards and backwards for a set of lines matching the context
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157 given in the hunk.
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158 First
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159 .I patch
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160 looks for a place where all lines of the context match.
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161 If no such place is found, and it's a context diff, and the maximum fuzz factor
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162 is set to 1 or more, then another scan takes place ignoring the first and last
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163 line of context.
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164 If that fails, and the maximum fuzz factor is set to 2 or more,
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165 the first two and last two lines of context are ignored,
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166 and another scan is made.
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167 (The default maximum fuzz factor is 2.)
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168 If
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169 .I patch
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170 cannot find a place to install that hunk of the patch, it will put the
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171 hunk out to a reject file, which normally is the name of the output file
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172 plus \*(L".rej\*(R" (\*(L"#\*(R" on systems that do not support
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173 long filenames).
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174 (Note that the rejected hunk will come out in context diff form whether the
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175 input patch was a context diff or a normal diff.
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176 If the input was a normal diff, many of the contexts will simply be null.)
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177 The line numbers on the hunks in the reject file may be different than
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178 in the patch file: they reflect the approximate location patch thinks the
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179 failed hunks belong in the new file rather than the old one.
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180 .PP
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181 As each hunk is completed, you will be told whether the hunk succeeded or
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182 failed, and which line (in the new file)
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183 .I patch
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184 thought the hunk should go on.
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185 If this is different from the line number specified in the diff you will
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186 be told the offset.
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187 A single large offset MAY be an indication that a hunk was installed in the
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188 wrong place.
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189 You will also be told if a fuzz factor was used to make the match, in which
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190 case you should also be slightly suspicious.
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191 .PP
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192 If no original file is specified on the command line,
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193 .I patch
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194 will try to figure out from the leading garbage what the name of the file
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195 to edit is.
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196 In the header of a context diff, the filename is found from lines beginning
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197 with \*(L"***\*(R" or \*(L"---\*(R", with the shortest name of an existing
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198 file winning.
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199 Only context diffs have lines like that, but if there is an \*(L"Index:\*(R"
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200 line in the leading garbage,
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201 .I patch
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202 will try to use the filename from that line.
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203 The context diff header takes precedence over an Index line.
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204 If no filename can be intuited from the leading garbage, you will be asked
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205 for the name of the file to patch.
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206 .PP
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207 If the original file cannot be found or is read-only, but a suitable
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208 SCCS or RCS file is handy,
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209 .I patch
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210 will attempt to get or check out the file.
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211 .PP
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212 Additionally, if the leading garbage contains a \*(L"Prereq: \*(R" line,
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213 .I patch
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214 will take the first word from the prerequisites line (normally a version
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215 number) and check the input file to see if that word can be found.
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216 If not,
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217 .I patch
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218 will ask for confirmation before proceeding.
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219 .PP
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220 The upshot of all this is that you should be able to say, while in a news
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221 interface, the following:
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222 .Sp
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223 | patch -d /usr/src/local/blurfl
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224 .Sp
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225 and patch a file in the blurfl directory directly from the article containing
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226 the patch.
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227 .PP
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228 If the patch file contains more than one patch,
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229 .I patch
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230 will try to apply each of them as if they came from separate patch files.
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231 This means, among other things, that it is assumed that the name of the file
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232 to patch must be determined for each diff listing,
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233 and that the garbage before each diff listing will
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234 be examined for interesting things such as filenames and revision level, as
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235 mentioned previously.
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236 You can give switches (and another original file name) for the second and
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237 subsequent patches by separating the corresponding argument lists
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238 by a \*(L'+\*(R'.
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239 (The argument list for a second or subsequent patch may not specify a new
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240 patch file, however.)
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241 .PP
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242 .I Patch
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243 recognizes the following switches:
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244 .TP 5
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245 .B \-b
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246 causes the next argument to be interpreted as the backup extension, to be
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247 used in place of \*(L".orig\*(R" or \*(L"~\*(R".
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248 .TP 5
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249 .B \-B
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250 causes the next argument to be interpreted as a prefix to the backup file
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251 name. If this argument is specified any argument from -b will be ignored.
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252 .TP 5
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253 .B \-c
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254 forces
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255 .I patch
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256 to interpret the patch file as a context diff.
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257 .TP 5
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258 .B \-d
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259 causes
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260 .I patch
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261 to interpret the next argument as a directory, and cd to it before doing
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262 anything else.
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263 .TP 5
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264 .B \-D
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265 causes
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266 .I patch
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267 to use the "#ifdef...#endif" construct to mark changes.
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268 The argument following will be used as the differentiating symbol.
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269 Note that, unlike the C compiler, there must be a space between the
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270 .B \-D
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271 and the argument.
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272 .TP 5
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273 .B \-e
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274 forces
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275 .I patch
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276 to interpret the patch file as an ed script.
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277 .TP 5
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278 .B \-E
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279 causes
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280 .I patch
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281 to remove output files that are empty after the patches have been applied.
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282 .TP 5
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283 .B \-f
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284 forces
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285 .I patch
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286 to assume that the user knows exactly what he or she is doing, and to not
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287 ask any questions. It assumes the following: skip patches for which a
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288 file to patch can't be found; patch files even though they have the
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289 wrong version for the ``Prereq:'' line in the patch; and assume that
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290 patches are not reversed even if they look like they are.
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291 This option does not suppress commentary; use
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292 .B \-s
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293 for that.
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294 .TP 5
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295 .B \-t
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296 similar to
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297 .BR \-f ,
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298 in that it suppresses questions, but makes some different assumptions:
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299 skip patches for which a file to patch can't be found (the same as \fB\-f\fP);
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300 skip patches for which the file has the wrong version for the ``Prereq:'' line
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301 in the patch; and assume that patches are reversed if they look like
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302 they are.
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303 .TP 5
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304 .B \-F<number>
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305 sets the maximum fuzz factor.
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306 This switch only applies to context diffs, and causes
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307 .I patch
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308 to ignore up to that many lines in looking for places to install a hunk.
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309 Note that a larger fuzz factor increases the odds of a faulty patch.
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310 The default fuzz factor is 2, and it may not be set to more than
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311 the number of lines of context in the context diff, ordinarily 3.
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312 .TP 5
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313 .B \-l
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314 causes the pattern matching to be done loosely, in case the tabs and
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315 spaces have been munged in your input file.
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316 Any sequence of whitespace in the pattern line will match any sequence
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317 in the input file.
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318 Normal characters must still match exactly.
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319 Each line of the context must still match a line in the input file.
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320 .TP 5
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321 .B \-n
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322 forces
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323 .I patch
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324 to interpret the patch file as a normal diff.
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325 .TP 5
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326 .B \-N
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327 causes
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328 .I patch
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329 to ignore patches that it thinks are reversed or already applied.
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330 See also
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331 .B \-R .
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332 .TP 5
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333 .B \-o
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334 causes the next argument to be interpreted as the output file name.
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335 .TP 5
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336 .B \-p<number>
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337 sets the pathname strip count,
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338 which controls how pathnames found in the patch file are treated, in case
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339 the you keep your files in a different directory than the person who sent
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340 out the patch.
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341 The strip count specifies how many slashes are to be stripped from
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342 the front of the pathname.
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343 (Any intervening directory names also go away.)
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344 For example, supposing the filename in the patch file was
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345 .sp
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346 /u/howard/src/blurfl/blurfl.c
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347 .sp
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348 setting
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349 .B \-p
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350 or
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351 .B \-p0
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352 gives the entire pathname unmodified,
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353 .B \-p1
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354 gives
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355 .sp
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356 u/howard/src/blurfl/blurfl.c
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357 .sp
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358 without the leading slash,
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359 .B \-p4
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360 gives
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361 .sp
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362 blurfl/blurfl.c
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363 .sp
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364 and not specifying
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365 .B \-p
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366 at all just gives you "blurfl.c", unless all of the directories in the
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367 leading path (u/howard/src/blurfl) exist and that path is relative,
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368 in which case you get the entire pathname unmodified.
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369 Whatever you end up with is looked for either in the current directory,
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370 or the directory specified by the
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371 .B \-d
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372 switch.
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373 .TP 5
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374 .B \-r
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375 causes the next argument to be interpreted as the reject file name.
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376 .TP 5
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377 .B \-R
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378 tells
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379 .I patch
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380 that this patch was created with the old and new files swapped.
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381 (Yes, I'm afraid that does happen occasionally, human nature being what it
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382 is.)
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383 .I Patch
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384 will attempt to swap each hunk around before applying it.
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385 Rejects will come out in the swapped format.
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386 The
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387 .B \-R
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388 switch will not work with ed diff scripts because there is too little
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389 information to reconstruct the reverse operation.
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390 .Sp
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391 If the first hunk of a patch fails,
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392 .I patch
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393 will reverse the hunk to see if it can be applied that way.
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394 If it can, you will be asked if you want to have the
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395 .B \-R
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396 switch set.
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397 If it can't, the patch will continue to be applied normally.
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398 (Note: this method cannot detect a reversed patch if it is a normal diff
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399 and if the first command is an append (i.e. it should have been a delete)
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400 since appends always succeed, due to the fact that a null context will match
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401 anywhere.
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402 Luckily, most patches add or change lines rather than delete them, so most
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403 reversed normal diffs will begin with a delete, which will fail, triggering
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404 the heuristic.)
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405 .TP 5
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406 .B \-s
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407 makes
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408 .I patch
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409 do its work silently, unless an error occurs.
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410 .TP 5
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411 .B \-S
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412 causes
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413 .I patch
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414 to ignore this patch from the patch file, but continue on looking
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415 for the next patch in the file.
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416 Thus
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417 .sp
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418 patch -S + -S + <patchfile
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419 .sp
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420 will ignore the first and second of three patches.
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421 .TP 5
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422 .B \-u
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423 forces
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424 .I patch
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425 to interpret the patch file as a unified context diff (a unidiff).
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426 .TP 5
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427 .B \-v
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428 causes
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429 .I patch
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430 to print out its revision header and patch level.
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431 .TP 5
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432 .B \-V
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433 causes the next argument to be interpreted as a method for creating
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434 backup file names. The type of backups made can also be given in the
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435 .B VERSION_CONTROL
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436 environment variable, which is overridden by this option.
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437 The
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438 .B -B
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439 option overrides this option, causing the prefix to always be used for
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440 making backup file names.
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441 The value of the
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442 .B VERSION_CONTROL
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443 environment variable and the argument to the
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444 .B -V
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445 option are like the GNU
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446 Emacs `version-control' variable; they also recognize synonyms that
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447 are more descriptive. The valid values are (unique abbreviations are
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448 accepted):
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449 .RS
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450 .TP
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451 `t' or `numbered'
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452 Always make numbered backups.
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453 .TP
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454 `nil' or `existing'
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455 Make numbered backups of files that already
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456 have them, simple backups of the others.
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457 This is the default.
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458 .TP
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459 `never' or `simple'
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460 Always make simple backups.
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461 .RE
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462 .TP 5
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463 .B \-x<number>
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464 sets internal debugging flags, and is of interest only to
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465 .I patch
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466 patchers.
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467 .SH AUTHOR
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468 Larry Wall <lwall@netlabs.com>
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469 .br
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470 with many other contributors.
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471 .SH ENVIRONMENT
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472 .TP
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473 .B TMPDIR
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474 Directory to put temporary files in; default is /tmp.
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475 .TP
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476 .B SIMPLE_BACKUP_SUFFIX
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477 Extension to use for backup file names instead of \*(L".orig\*(R" or
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478 \*(L"~\*(R".
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479 .TP
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480 .B VERSION_CONTROL
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481 Selects when numbered backup files are made.
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482 .SH FILES
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483 $TMPDIR/patch*
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484 .SH SEE ALSO
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485 diff(1)
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486 .SH NOTES FOR PATCH SENDERS
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487 There are several things you should bear in mind if you are going to
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488 be sending out patches.
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489 First, you can save people a lot of grief by keeping a patchlevel.h file
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490 which is patched to increment the patch level as the first diff in the
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491 patch file you send out.
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492 If you put a Prereq: line in with the patch, it won't let them apply
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493 patches out of order without some warning.
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494 Second, make sure you've specified the filenames right, either in a
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495 context diff header, or with an Index: line.
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496 If you are patching something in a subdirectory, be sure to tell the patch
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497 user to specify a
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498 .B \-p
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499 switch as needed.
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500 Third, you can create a file by sending out a diff that compares a
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501 null file to the file you want to create.
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502 This will only work if the file you want to create doesn't exist already in
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503 the target directory.
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504 Fourth, take care not to send out reversed patches, since it makes people wonder
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505 whether they already applied the patch.
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506 Fifth, while you may be able to get away with putting 582 diff listings into
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507 one file, it is probably wiser to group related patches into separate files in
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508 case something goes haywire.
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509 .SH DIAGNOSTICS
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510 Too many to list here, but generally indicative that
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511 .I patch
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512 couldn't parse your patch file.
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513 .PP
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514 The message \*(L"Hmm...\*(R" indicates that there is unprocessed text in
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515 the patch file and that
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516 .I patch
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517 is attempting to intuit whether there is a patch in that text and, if so,
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518 what kind of patch it is.
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519 .PP
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520 .I Patch
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521 will exit with a non-zero status if any reject files were created.
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522 When applying a set of patches in a loop it behooves you to check this
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523 exit status so you don't apply a later patch to a partially patched file.
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524 .SH CAVEATS
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525 .I Patch
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526 cannot tell if the line numbers are off in an ed script, and can only detect
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527 bad line numbers in a normal diff when it finds a \*(L"change\*(R" or
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528 a \*(L"delete\*(R" command.
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529 A context diff using fuzz factor 3 may have the same problem.
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530 Until a suitable interactive interface is added, you should probably do
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531 a context diff in these cases to see if the changes made sense.
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532 Of course, compiling without errors is a pretty good indication that the patch
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533 worked, but not always.
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534 .PP
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535 .I Patch
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536 usually produces the correct results, even when it has to do a lot of
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537 guessing.
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538 However, the results are guaranteed to be correct only when the patch is
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539 applied to exactly the same version of the file that the patch was
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540 generated from.
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541 .SH BUGS
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542 Could be smarter about partial matches, excessively \&deviant offsets and
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543 swapped code, but that would take an extra pass.
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544 .PP
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545 If code has been duplicated (for instance with #ifdef OLDCODE ... #else ...
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546 #endif),
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547 .I patch
|
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548 is incapable of patching both versions, and, if it works at all, will likely
|
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549 patch the wrong one, and tell you that it succeeded to boot.
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550 .PP
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551 If you apply a patch you've already applied,
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552 .I patch
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553 will think it is a reversed patch, and offer to un-apply the patch.
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554 This could be construed as a feature.
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555 .rn }` ''
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