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38 lines
1.0 KiB
Markdown
38 lines
1.0 KiB
Markdown
6 years ago
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# Patching
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A patch is a source code that updates other source code. It is formatted as a diff, because it represents what is different between two versions of text. You create a __diff__ with thie `diff` utility, which is then applied to the source code using the `patch` utility.
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_NOTE_: Other version control systems like git provide their own methods of creating diffs or patching software.
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This is an example where we are creating a patch from the original source code using `diff` and then applying it via `patch`.
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## Patching in 6 easy-ish steps
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Preserve the original source code
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```bash
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cp cello.c cello.c.orig
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```
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Change the source code
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Generate a patch using the `diff` utility
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```bash
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diff -Naur cello.c.orig cello.c
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```
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Save the patch to a file
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```bash
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diff -Naur cello.c.orig cello.c > cello-output-first-patch.patch
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```
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Restore the original file
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```bash
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cp cello.c.orig cello.c
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```
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Patch the original with the contents of the new patch file using the `patch` utility
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```bash
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patch < cello-output-first.patch
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```
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