Unix Patch File

In a shell, type: which diff which patch This should return the paths to diff and patch, as diff and patch are two of the most fundamental utilities in a Unix system. change to the directory where the file you wish to make a patch for is located.

Jan 26, 2015 - This page explains how you can make a patch file. Patch is a standard format, and there are many options for how to create one. Pick the one.

The computer tool patch is a Unix program that updates text files according to instructions contained in a separate file, called a patch file. The patch file also  History -  Usage context -  Patches in software development -  Usage examplesHowTo Apply a Patch File To My Linux / UNIX Source Codewww.cyberciti.biz/faq/appy-patch-file-using-patch-command/CachedSimilarApr 29, 2014 - I also know that I can patch binary package using up2date or yum command in Linux. I was wondering is if there s a way to apply a patch file to downloaded source code on a Linux / UNIX like operating system source tree. There is a command called patch that apply a diff file or.

Patch files are files created with the Unix command diff that are applied using the command patch to modify text files to fix bugs or extend functionality.

Sep 18, 2012 - The commands diff and patch form a powerful combination. They are widely used to get differences between original files and updated files in.

Patch takes a patch file patchfile containing a difference listing produced by the dates and times in Universal Time using traditional Unix format, so that patch.

Dec 2, 2014 - This tutorial explains how to create a patch file using diff, and apply it using. Sed and Awk 101 Hacks eBook - Enhance Your UNIX / Linux Life.

Applying patches, modifying files according to instructions in the patch file, is the Patch can be found on most UNIX systems and is included in the packages.

I am a new Linux and Unix system user. I also know that I can patch binary package using up2date or yum command in Linux. I was wondering is if there s a way to apply a patch file to downloaded source code on a Linux / UNIX like operating system source tree.

Linux and UNIX source software often comes with security and other patches. You can download them from Internet or project home page. There is a command called patch that apply a diff file or patch to an original source tree.

Tutorial detailsDifficultyEasy rss Root privilegesNoRequirementspatch and diff commandsEstimated completion time5m

The patch command takes a patch file patchfile containing a difference listing produced by the diff program and applies those differences to one or more original files, producing patched versions. Normally the patched versions are put in place of the originals.patch command syntax

The basic syntax is as follows:

To apply a patch, one could run the following command in a shell:

In this example, patch foo.c with patch.diff file:

Patches can be undone, or reversed, with the -R option:

patch -R How do I create a patch.

To create a patch, one could run the following diff command:

diff -u oldfile-name-here newfile-name-here patch.diff Example: Creating and applying the patch for hello.c sample program on a Linux or Unix like system

Make a copy of the hello.c or file you wish to modify ; both files must be in the same directory, though it may be any directory using cp command:

Edit the file hello-new.c to make it as you want it. In this example, I am fixing a few compiler warning by adding return value from main : include

Next, use command diff to create a unified diff patch file called hello.patch:

diff -u hello.c hello-new.c hello.patch

To see patch use cat command as follows:

Sample outputs:--- hello.c 2014-04-29 :49.000000000 0530

hello-new.c 2014-04-29 :43.000000000 0530

To apply the patch from hello.patch, enter: The hello.patch patchfile knows the name of the file to be patched

Sample outputs:patching file hello.c

Finally, here is my updated and patched hello.c:

Sample outputs:Hello, world.A note about working on an entire source tree

First, make a copy of the source tree:

Original source code is in lighttpd-1.4.35/ directory

cp -R lighttpd-1.4.35/ lighttpd-1.4.35-new/

Cd to lighttpd-1.4.35-new directory and make changes as per your requirements:

Finally, create a patch with the following command:

diff -rupN lighttpd-1.4.35/ lighttpd-1.4.35-new/ my.patch

You can use my.patch file to patch lighttpd-1.4.35 source code on a different computer/server using patch command as discussed above:

See the man page of patch and other command for more information and usage - patch 1, diff 1, bash 1 Tweet itFacebook itGoogle itPDF itFound an error/typo on this page.

HowTo Apply a Patch File To My Linux / UNIX Source Code

When there is a security fix available for a particular software, we typically do a binary upgrade using the package management tools like yum or apt-get.

But, there might be situation where you have installed a software by compiling it from the source code.

In those situation, how do you apply the security fix to the software.

The answer is to download the security patch and apply it to the original source code and re-compile the software.

This tutorial explains how to create a patch file using diff, and apply it using patch command.

A patch file is a text file which contains the differences between two versions of the same file or same source-tree. Patch file is created by using diff command.

1. Create a Patch File using diff

To understand this, let us create a small C program named hello.c

Now, copy the hello.c to hello_new.c

Edit the hello_new.c as shown below to make some small changes:

Finally, create the patch file using diff command as shown below:

diff -u hello.c hello_new.c hello.patch

The above command will create a patch file named hello.patch.

--- hello.c 2014-10-07 :49.000000000 0530

hello_new.c 2014-10-07 :54.000000000 0530

2. Apply Patch File using Patch Command

The patch command takes a patch file as input and apply the differences to one or more original file s, producing patched versions.

patch options originalfile patchfile

Use the patch command as shown below to apply the hello.patch to the original hello.c source code.

The hello.patch file contains the name of the file to be patched. Once the file is patched, both hello.c and hello_new.c will have the content.

3. Create a Patch From a Source Tree

The above example was so simple that it works only with one file. We will see how to create and apply patch for a complete source tree by taking openvpn source code as example.

I ve downloaded 2 version of openvpn, openvpn-2.3.2 and openvpn-2.3.4.

tar -xvzf openvpn-2.3.2.tar.gz

tar -xvzf openvpn-2.3.4.tar.gz

Now we will create the patch using the following command.

diff -Naur /usr/src/openvpn-2.3.2 /usr/src/openvpn-2.3.4 openvpn.patch

The above command will operate recursively and find the differences, and place those differences in the patch file.

4. Apply Patch File to a Source Code Tree

The following patch commands can be used to apply the patch to source tree.

patching file openvpn-2.3.2/aclocal.m4

patching file openvpn-2.3.2/build/Makefile.in

patching file openvpn-2.3.2/build/msvc/Makefile.in

Please note that we are executing the command from /usr/src/. The patch file contains all the filenames in absolute path format from root . So when we execute from /usr/src, without the -p option, it will not work properly.

-p3 tells the patch command to skip 3 leading slashes from the filenames present in the patch file. In our case, the filename in patch file is /usr/src/openvpn-2.3.2/aclocal.m4, since you have given -p3, 3 leading slashes, i.e. until /usr/src/ is ignored.

5. Take a Backup before Applying the Patch using -b

You can take a backup of the original file before applying the patch command using the -b option as shown below.

Now you will have a file name hello.c.orig, which is the backup of the original hello.c.

You can also use -V to decide the backup filename format as shown below. Now you will have a file name hello.c. 1.

patch -b -V numbered hello.patch

6. Validate the Patch without Applying Dry-run Patch File

You can dry run the patch command to see if you are getting any errors, without patching the file using –dry-run option as shown below.

You can see that hello.c is not modified at all.

7. Reverse a Patch that is Already Applied Undo a Patch

You can use the -R option to reverse a patch which is applied already.

-rw-r--r-- 1 lakshmanan users 94 2014-10-07 hello.c

-rw-r--r-- 1 lakshmanan users 62 2014-10-07 hello.c

You can notice from the filesize, that the patch, which is applied already is reversed when we used the -R option.

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