Daily Archives: 17 November 2017

How to find lines that contain only lowercase characters

To print all lines that contain only lower case characters, we used the following regular expression in grep:

egrep '^[[:lower:]]+$' <file>;
#If you do not have egrep, use
grep -e '^[[:lower:]]+$' <file>;

Breakdown of the above regular expression:

  • ^ instructs the regular expression parser that the pattern should always start with the beginning of the line
  • [[:lower:]] this special instruction informs us that only lower case characters can match it
  • + the plus sign causes the preceding token to be matched one or more times
  • $ signifies the end of the line

My .gitignore file is ignored by git and it does not work 10

Some times, even if you haven’t added some files to the repository, git seems to monitor them even after you add them to the .gitignore file.

This is a caching issue that can occur and to fix it, you need to clear your cache.

NOTE : Before proceeding with this solution, commit all changes you do not want to lose!

.. then execute the following commands from the root folder of your repository:
The following, will untrack every file that is in your .gitignore:

git rm -r --cached .;
git add .;
git commit -m "Untracked files issue resolved to fix .gitignore";

git-rm removes files from the index, or from the working tree and the index. git rm will not remove a file from just your working directory. (There is no option to remove a file only from the working tree and yet keep it in the index; use /bin/rm if you want to do that.) The files being removed have to be identical to the tip of the branch, and no updates to their contents can be staged in the index, though that default behavior can be overridden with the -f option. When --cached is given, the staged content has to match either the tip of the branch or the file on disk, allowing the file to be removed from just the index.

-r allows recursive removal when a leading directory name is given.

--cached unstages and removes paths only from the index. Working tree files, whether modified or not, will be left alone.

From: git-rm

To stop tracking a single file file but not delete it from your filesystem use the following:

git rm --cached <file>;

Another issue: file removed from .gitignore filters does not appear to be tracked

When you remove something from .gitignore file and the file does not appear to be tracked, you can add it manually as follows:

git add -f <file>;
git commit -m "Re-Adding ignored file by force";

How to add untracked files to a git patch

Recently, we had to create a git patch for the deployment of a 3rd party repository in our code.
Some of the changes we had to apply using the patch mechanism was the creation of a few new files.
We did not want to have an external script to copy the new files to the appropriate locations, so we had to include those new files in the git patch somehow.
The git diff command (with the parameter -p or --patch) that generates the patch, it ignored the untracked files and so they did not appear in the patch.
To make the untracked files visible to the git diff command, we staged them (using git add) and then used the following command to create the patch:

git diff --patch --staged;

git diff [--options] --cached [<commit>] [--] [<path>...]
git diff [--options] --staged [<commit>] [--] [<path>...]
Adding the parameter --staged or --cached allows you to view the changes you staged for the next commit relative to the named <commit>. Typically you would want comparison with the latest commit, so if you do not give <commit>, it defaults to HEAD. If HEAD does not exist (e.g. unborned branches) and <commit> is not given, it shows all staged changes. --staged is a synonym of --cached.
From: man git-diff

In the end our commands to create the patch with the new files and apply it on a new clone of the 3rd party repository was as follows:

#In the folder of the modified repository, where the new files are staged
git diff -p --staged > ~/new.file.patch.diff;
#In the folder of the new clone of the repository, where the new files need to be created
git apply ~/new.file.patch.diff;

Ignore all edits to a file that is committed in git

Recently, we were working on a project that had committed in the source code a configuration file. That configuration file had hard-coded the production system values, so we had to modify them to the development system values before using it.

To avoid committing the configuration file with the development parameters by accident, we instructed git to ignore any changes that were made to it using the following command.

git update-index --assume-unchanged <file>;

By doing so, git assumed that the file was always unchanged and it never showed up in the git status results nor was staged when git add . was used etc.

After we were done with development (and whenever we needed to pull the branch for changes or checkout another branch) we removed the file from the list of ignored files using the following command.

git update-index --no-assume-unchanged <file>;

Using this command, git would start again to monitor changes to the file and merge it or update it or push it when needed as it would normally do for any file not included in the .gitignore file. The best part of this trick is that you do not have to update the .gitignore file to achieve the task of ignoring a file.

More information

git update-index modifies the index or directory cache. Each file mentioned is updated into the index and any unmerged or needs updating state is cleared.

--[no-]assume-unchanged When these flags are specified, the object names recorded for the paths are not updated. Instead, these options set and unset the “assume unchanged” bit for the paths. When the “assume unchanged” bit is on, Git stops checking the working tree files for possible modifications, so you need to manually unset the bit to tell Git when you change the working tree file. This is sometimes helpful when working with a big project on a filesystem that has very slow lstat(2) system call (e.g. cifs).

This option can be also used as a coarse file-level mechanism to ignore uncommitted changes in tracked files (akin to what .gitignore does for untracked files). Git will fail (gracefully) in case it needs to modify this file in the index e.g. when merging in a commit; thus, in case the assumed-untracked file is changed upstream, you will need to handle the situation manually.

From: man git-update-index


In case you are wondering on how to see which files are currently ignored in your local repository copy by the git update-index --assume-unchanged <file>; command, you can use the following code:

git ls-files -v | grep -e '^[[:lower:]]';

git ls-files -v will print out all objects that git knows and the -v parameter will print all flags associated with them. The files that are ignored because of the
git update-index --assume-unchanged <file>; command will be printed each one on a different line that starts with a lower case character. So, to get all files that are ignored by the git update-index --assume-unchanged <file>; command, we need to grep the results of git ls-files -v for lines that start with a lower case.

git-ls-files shows information about files in the index and the working tree.
It merges the file listing in the directory cache index with the actual working directory list, and shows different combinations of the two.

-v Similar to -t (below), but use lowercase letters for files that are marked as assume unchanged (see git-update-index(1)).

-t This feature is semi-deprecated. For scripting purpose, git-status(1)–porcelain and git-diff-files(1)–name-status are almost always superior alternatives, and users should look at git-status(1)–short or git-diff(1)–name-status for more user-friendly alternatives.
This option identifies the file status with the following tags (followed by a space) at the start of each line:

An additional interesting parameter for git ls-files is
-i, --ignored Shows only ignored files in the output. When showing files in the index, it prints only those matched by an exclude pattern. When showing “other” files, it shows only those matched by an exclude pattern.

--exclude-standard Add the standard Git exclusions: .git/info/exclude, .gitignore in each directory, and the user’s global exclusion file.
From: man git-ls-files

Examples for git ls-files -i, –ignored and –exclude-standard

# Show files in the index that are ignored because of patterns in .gitignore
git ls-files --ignored --exclude-from=.gitignore;
# Show other (i.e. untracked) files that are ignored because of patterns in .gitignore
git ls-files --ignored --other --exclude-from=.gitignore;
# Show files in the index that are ignored because of patterns in any of the standard git exclusions.
git ls-files --ignored --exclude-standard;
# Show other (i.e. untracked) files that are ignored because of patterns in any of the standard git exclusions.
git ls-files --ignored --exclude-standard --other;