Say I have a diff file looking basically like the following.
+line a
-line b
Is it possible to do one (or both) of the following:
Inverse this file (so I'd get)
-line a
+line b
Pass some argument to patch so the end result the same as applying
the inversed diff file described above
You can leave the diff as is and apply in reverse
git apply --reverse backwards-diff
Here is what you should do (assuming newFile.txt is the file you want to apply the reversed diff file on and diffFile.txt is the diff file):
patch -R newFile.txt diffFile.txt -o oldFile.txt
To rewrite a reversed / inverted diff file, use interdiff from diffutils:
interdiff -q my-diff-file /dev/null
Related
Not git diff, just plain diff or an equivalent tool: How to diff files using another diff algorithm, like histogram? I'm tired of seeing unrelated curly braces being matched up.
I tried diff --minimal, but it wasn't noticeably better for the differences I'm looking at.
This turns up nothing:
diff --help | grep -i histogram
man 1 diff | grep -i histogram
Is there a better diff tool or method for diffing files?
In a folder I have many files with several parameters in filenames, e.g (just with one parameter) file_a1.0.txt, file_a1.2.txt etc.
These are generated by a c++ code and I'd need to take the last one (in time) generated. I don't know a priori what will be the value of this parameter when the code is terminated. After that I need to copy the 2nd line of this last file.
To copy the 2nd line of the any file, I know that this sed command works:
sed -n 2p filename
I know also how to find the last generated file:
ls -rtl file_a*.txt | tail -1
Question:
how to combine these two operation? Certainly it is possible to pipe the 2nd operation to that sed operation but I dont know how to include filename from pipe as input to that sed command.
You can use this,
ls -rt1 file_a*.txt | tail -1 | xargs sed -n '2p'
(OR)
sed -n '2p' `ls -rt1 file_a*.txt | tail -1`
sed -n '2p' $(ls -rt1 file_a*.txt | tail -1)
Typically you can put a command in back ticks to put its output at a particular point in another command - so
sed -n 2p `ls -rt name*.txt | tail -1 `
Alternatively - and preferred, because it is easier to nest etc -
sed -n 2p $(ls -rt name*.txt | tail -1)
-r in ls is reverse order.
-r, --reverse
reverse order while sorting
But it is not good idea when used it with tail -1.
With below change (head -1 without r option in ls), performance will be better, that you needn't wait to list all files then pipe to tail command
sed -n 2p $(ls -t1 name*.txt | head -1 )
I was looking for a similar solution: taking the file names from a pipe of grep results to feed to sed. I've copied my answer here for the search & replace, but perhaps this example can help as it calls sed for each of the names found in the pipe:
this command to simply find all the files:
grep -i -l -r foo ./*
this one to exclude this_shell.sh (in case you put the command in a script called this_shell.sh), tee the output to the console to see what happened, and then use sed on each file name found to replace the text foo with bar:
grep -i -l -r --exclude "this_shell.sh" foo ./* | tee /dev/fd/2 | while read -r x; do sed -b -i 's/foo/bar/gi' "$x"; done
I chose this method, as I didn't like having all the timestamps changed for files not modified. Feeding the grep result allows only the files with target text to be looked at (thus likely may improve performance / speed as well)
be sure to backup your files & test before using. May not work in some environments for files with embedded spaces. (?)
fwiw - I had some problems using the tail method, it seems that the entire dataset was generated before calling tail on just the last item.
I'd need to see what has been changed between two directories which contain different version of a software sourcecode. While I have found a way to get a unique .diff file, how can I obtain a different file for each changed file in the two directories? I'd need this, as the "main" is about 6 MB and wanted some more handy thing.
I came around this problem too, so I ended up with some lines of a shell script. It takes three arguments: Source and destination directory (as used for diff) and a target folder (should exist) for the output.
It's a bit hacky, but maybe it would be useful for someone. So use with care, especially if your paths have special characters.
#!/bin/sh
DIFFARGS="-wb"
LANG=C
TARGET=$3
SRC=`echo $1 | sed -e 's/\//\\\\\\//g'`
DST=`echo $2 | sed -e 's/\//\\\\\\//g'`
if [ ! -d "$TARGET" ]; then
echo "'$TARGET' is not a directory." >&2
exit 1
fi
diff -rqN $DIFFARGS "$1" "$2" | sed "s/Files $SRC\/\(.*\?\) and $DST\/\(.*\?\) differ/\1/" | \
while read file
do
if [ ! -d "$TARGET/`dirname \"$file\"`" ]; then
mkdir -p "$TARGET/`dirname \"$file\"`"
fi
diff $DIFFARGS -N "$1/$file" "$2/$file" > "$TARGET"/"$file.diff"
done
if you want to compare source code it is better to commit it to a source vesioning program as "svn".
after you have done so. do a diff of your uploaded code and pipe it to file.diff
svn diff --old svn:url1 --new svn:url2 > file.diff
A bash for loop will work for you. The following will diff two directories with C source code and produce a separate diff for each file.
for FILE in $(find <FIRST_DIR> -name '*.[ch]'); do DIFF=<DIFF_DIR>/$(echo $FILE | grep -o '[-_a-zA-Z0-9.]*$').diff; diff -u $FILE <SECOND_DIR>/$FILE > $DIFF; done
Use the correct patch level for the lines starting with +++
I have a patch file containing the output from git diff. I want to get a summary of all the files that, according to the patch file, have been added or modified. What command can I use to achieve this?
patchutils includes a lsdiff utility.
grep '+++' mydiff.patch seems to do the trick.
I can also use git diff --names-only which is probably the better approach.
grep '+++' mydiff.patch|perl -pe 's/\+\+\+ //g'
Details:
git diff produces output in the format
+++ b/file
So if you're using grep as Nathan suggested
grep '+++' mydiff.patch
You'll have the list of affected files, prepended by '+++ ' (3 plus signs and a space).
I often need to further process files and find it convenient to have one filename per line without anything else. This can be achieved with the following command, where perl/regex removes these plus signs and the space.
grep '+++' mydiff.patch|perl -pe 's/\+\+\+ //g'
For patch files generated with diff -Naur, the mydiff.patch file contains entries with filename and date ( is indicating the tabulator whitespace character)
+++ b/file<tab>2013-07-03 13:58:45.000000000 +0200
To extract the filenames for this, use
grep '+++' mydiff.patch|perl -pe 's/\+\+\+ (.*)\t.*/\1/g'
A decent way to do this is to use the --stat flag (or the --summary flag, if you need only new / deleted / renamed files for some reason).
Example:
git apply --stat peer.diff | awk '{ print $1 }' | sed '$d'
1-js/03-code-quality/index.md
CONTR.md
LICENSE.md
README.md
chat-app.readme.md
When you parse patches generated by git format-patch or others containing additional information about number of lines edited, it's crucial to search for ^+++ (at the start of the line) rather than just +++.
For example:
grep '^+++' *.patch | sed -e 's#+++ [ab]/##'
will output paths without a/ or b/ at the begin.
When using Diff, how would one go about ignoring line differences that only diff on GUID's? Something along the lines of:
diff -I "^.*[a-zA-Z0-9]{8}\-[a-zA-Z0-9]{4}\-[a-zA-Z0-9]{5}\-[a-zA-Z0-9]{5}\-[a-zA-Z0-9]{12}.*$"
Where obviously the above doesn't work, but just to get an idea of what is needed.
diff -I '[0-9A-F\-]\{36\}' foo.txt bar.txt
Perhaps you could first pipe the input files through sed to remove anything matching a GUID, then perform the diff.
Can you pipe the output of diff to a grep -v and use your pattern?