git-rebase(1)
NAME
git-rebase - Reapply commits on top of another base tip
SYNOPSIS
git rebase [-i | --interactive] [options] [--exec <cmd>] [--onto <newbase>]
[<upstream> [<branch>]]
git rebase [-i | --interactive] [options] [--exec <cmd>] [--onto <newbase>]
--root [<branch>]
git rebase --continue | --skip | --abort | --edit-todo
DESCRIPTION
If <branch> is specified, git rebase will perform an automatic git checkout <branch> before doing anything else. Otherwise it remains on the current branch. If <upstream> is not specified, the upstream configured in branch.<name>.remote and branch.<name>.merge options will be used (see git-config(1) for details) and the --fork-point option is assumed. If you are currently not on any branch or if the current branch does not have a configured upstream, the rebase will abort. All changes made by commits in the current branch but that are not in <upstream> are saved to a temporary area. This is the same set of commits that would be shown by git log <upstream>..HEAD; or by git log 'fork_point'..HEAD, if --fork-point is active (see the description on --fork-point below); or by git log HEAD, if the --root option is specified. The current branch is reset to <upstream>, or <newbase> if the --onto option was supplied. This has the exact same effect as git reset --hard <upstream> (or <newbase>). ORIG_HEAD is set to point at the tip of the branch before the reset. The commits that were previously saved into the temporary area are then reapplied to the current branch, one by one, in order. Note that any commits in HEAD which introduce the same textual changes as a commit in HEAD..<upstream> are omitted (i.e., a patch already accepted upstream with a different commit message or timestamp will be skipped). It is possible that a merge failure will prevent this process from being completely automatic. You will have to resolve any such merge failure and run git rebase --continue. Another option is to bypass the commit that caused the merge failure with git rebase --skip. To check out the original <branch> and remove the .git/rebase-apply working files, use the command git rebase --abort instead. Assume the following history exists and the current branch is "topic": A---B---C topic / D---E---F---G master From this point, the result of either of the following commands: git rebase master git rebase master topic would be: A'--B'--C' topic / D---E---F---G master NOTE: The latter form is just a short-hand of git checkout topic followed by git rebase master. When rebase exits topic will remain the checked-out branch. If the upstream branch already contains a change you have made (e.g., because you mailed a patch which was applied upstream), then that commit will be skipped. For example, running git rebase master on the following history (in which A' and A introduce the same set of changes, but have different committer information): A---B---C topic / D---E---A'---F master will result in: B'---C' topic / D---E---A'---F master Here is how you would transplant a topic branch based on one branch to another, to pretend that you forked the topic branch from the latter branch, using rebase --onto. First let's assume your topic is based on branch next. For example, a feature developed in topic depends on some functionality which is found in next. o---o---o---o---o master \ o---o---o---o---o next \ o---o---o topic We want to make topic forked from branch master; for example, because the functionality on which topic depends was merged into the more stable master branch. We want our tree to look like this: o---o---o---o---o master | \ | o'--o'--o' topic \ o---o---o---o---o next We can get this using the following command: git rebase --onto master next topic Another example of --onto option is to rebase part of a branch. If we have the following situation: H---I---J topicB / E---F---G topicA / A---B---C---D master then the command git rebase --onto master topicA topicB would result in: H'--I'--J' topicB / | E---F---G topicA |/ A---B---C---D master This is useful when topicB does not depend on topicA. A range of commits could also be removed with rebase. If we have the following situation: E---F---G---H---I---J topicA then the command git rebase --onto topicA~5 topicA~3 topicA would result in the removal of commits F and G: E---H'---I'---J' topicA This is useful if F and G were flawed in some way, or should not be part of topicA. Note that the argument to --onto and the <upstream> parameter can be any valid commit-ish. In case of conflict, git rebase will stop at the first problematic commit and leave conflict markers in the tree. You can use git diff to locate the markers (<<<<<<) and make edits to resolve the conflict. For each file you edit, you need to tell Git that the conflict has been resolved, typically this would be done with git add <filename> After resolving the conflict manually and updating the index with the desired resolution, you can continue the rebasing process with git rebase --continue Alternatively, you can undo the git rebase with git rebase --abort
CONFIGURATION
rebase.stat
Whether to show a diffstat of what changed upstream since the last
rebase. False by default.
rebase.autoSquash
If set to true enable --autosquash option by default.
rebase.autoStash
If set to true enable --autostash option by default.
rebase.missingCommitsCheck
If set to "warn", print warnings about removed commits in
interactive mode. If set to "error", print the warnings and stop
the rebase. If set to "ignore", no checking is done. "ignore" by
default.
rebase.instructionFormat
Custom commit list format to use during an --interactive rebase.
OPTIONS
--onto <newbase>
Starting point at which to create the new commits. If the --onto
option is not specified, the starting point is <upstream>. May be
any valid commit, and not just an existing branch name.
As a special case, you may use "A...B" as a shortcut for the merge
base of A and B if there is exactly one merge base. You can leave
out at most one of A and B, in which case it defaults to HEAD.
<upstream>
Upstream branch to compare against. May be any valid commit, not
just an existing branch name. Defaults to the configured upstream
for the current branch.
<branch>
Working branch; defaults to HEAD.
--continue
Restart the rebasing process after having resolved a merge
conflict.
--abort
Abort the rebase operation and reset HEAD to the original branch.
If <branch> was provided when the rebase operation was started,
then HEAD will be reset to <branch>. Otherwise HEAD will be reset
to where it was when the rebase operation was started.
--keep-empty
Keep the commits that do not change anything from its parents in
the result.
--skip
Restart the rebasing process by skipping the current patch.
--edit-todo
Edit the todo list during an interactive rebase.
-m, --merge
Use merging strategies to rebase. When the recursive (default)
merge strategy is used, this allows rebase to be aware of renames
on the upstream side.
Note that a rebase merge works by replaying each commit from the
working branch on top of the <upstream> branch. Because of this,
when a merge conflict happens, the side reported as ours is the
so-far rebased series, starting with <upstream>, and theirs is the
working branch. In other words, the sides are swapped.
-s <strategy>, --strategy=<strategy>
Use the given merge strategy. If there is no -s option git
merge-recursive is used instead. This implies --merge.
Because git rebase replays each commit from the working branch on
top of the <upstream> branch using the given strategy, using the
ours strategy simply discards all patches from the <branch>, which
makes little sense.
-X <strategy-option>, --strategy-option=<strategy-option>
Pass the <strategy-option> through to the merge strategy. This
implies --merge and, if no strategy has been specified, -s
recursive. Note the reversal of ours and theirs as noted above for
the -m option.
-S[<keyid>], --gpg-sign[=<keyid>]
GPG-sign commits. The keyid argument is optional and defaults to
the committer identity; if specified, it must be stuck to the
option without a space.
-q, --quiet
Be quiet. Implies --no-stat.
-v, --verbose
Be verbose. Implies --stat.
--stat
Show a diffstat of what changed upstream since the last rebase. The
diffstat is also controlled by the configuration option
rebase.stat.
-n, --no-stat
Do not show a diffstat as part of the rebase process.
--no-verify
This option bypasses the pre-rebase hook. See also githooks(5).
--verify
Allows the pre-rebase hook to run, which is the default. This
option can be used to override --no-verify. See also githooks(5).
-C<n>
Ensure at least <n> lines of surrounding context match before and
after each change. When fewer lines of surrounding context exist
they all must match. By default no context is ever ignored.
-f, --force-rebase
Force a rebase even if the current branch is up-to-date and the
command without --force would return without doing anything.
You may find this (or --no-ff with an interactive rebase) helpful
after reverting a topic branch merge, as this option recreates the
topic branch with fresh commits so it can be remerged successfully
without needing to "revert the reversion" (see the
revert-a-faulty-merge How-To[1] for details).
--fork-point, --no-fork-point
Use reflog to find a better common ancestor between <upstream> and
<branch> when calculating which commits have been introduced by
<branch>.
When --fork-point is active, fork_point will be used instead of
<upstream> to calculate the set of commits to rebase, where
fork_point is the result of git merge-base --fork-point <upstream>
<branch> command (see git-merge-base(1)). If fork_point ends up
being empty, the <upstream> will be used as a fallback.
If either <upstream> or --root is given on the command line, then
the default is --no-fork-point, otherwise the default is
--fork-point.
--ignore-whitespace, --whitespace=<option>
These flag are passed to the git apply program (see git-apply(1))
that applies the patch. Incompatible with the --interactive option.
--committer-date-is-author-date, --ignore-date
These flags are passed to git am to easily change the dates of the
rebased commits (see git-am(1)). Incompatible with the
--interactive option.
-i, --interactive
Make a list of the commits which are about to be rebased. Let the
user edit that list before rebasing. This mode can also be used to
split commits (see SPLITTING COMMITS below).
The commit list format can be changed by setting the configuration
option rebase.instructionFormat. A customized instruction format
will automatically have the long commit hash prepended to the
format.
-p, --preserve-merges
Recreate merge commits instead of flattening the history by
replaying commits a merge commit introduces. Merge conflict
resolutions or manual amendments to merge commits are not
preserved.
This uses the --interactive machinery internally, but combining it
with the --interactive option explicitly is generally not a good
idea unless you know what you are doing (see BUGS below).
-x <cmd>, --exec <cmd>
Append "exec <cmd>" after each line creating a commit in the final
history. <cmd> will be interpreted as one or more shell commands.
You may execute several commands by either using one instance of
--exec with several commands:
git rebase -i --exec "cmd1 && cmd2 && ..."
or by giving more than one --exec:
git rebase -i --exec "cmd1" --exec "cmd2" --exec ...
If --autosquash is used, "exec" lines will not be appended for the
intermediate commits, and will only appear at the end of each
squash/fixup series.
This uses the --interactive machinery internally, but it can be run
without an explicit --interactive.
--root
Rebase all commits reachable from <branch>, instead of limiting
them with an <upstream>. This allows you to rebase the root
commit(s) on a branch. When used with --onto, it will skip changes
already contained in <newbase> (instead of <upstream>) whereas
without --onto it will operate on every change. When used together
with both --onto and --preserve-merges, all root commits will be
rewritten to have <newbase> as parent instead.
--autosquash, --no-autosquash
When the commit log message begins with "squash! ..." (or "fixup!
..."), and there is a commit whose title begins with the same ...,
automatically modify the todo list of rebase -i so that the commit
marked for squashing comes right after the commit to be modified,
and change the action of the moved commit from pick to squash (or
fixup). Ignores subsequent "fixup! " or "squash! " after the first,
in case you referred to an earlier fixup/squash with git commit
--fixup/--squash.
This option is only valid when the --interactive option is used.
If the --autosquash option is enabled by default using the
configuration variable rebase.autoSquash, this option can be used
to override and disable this setting.
--autostash, --no-autostash
Automatically create a temporary stash before the operation begins,
and apply it after the operation ends. This means that you can run
rebase on a dirty worktree. However, use with care: the final stash
application after a successful rebase might result in non-trivial
conflicts.
--no-ff
With --interactive, cherry-pick all rebased commits instead of
fast-forwarding over the unchanged ones. This ensures that the
entire history of the rebased branch is composed of new commits.
Without --interactive, this is a synonym for --force-rebase.
You may find this helpful after reverting a topic branch merge, as
this option recreates the topic branch with fresh commits so it can
be remerged successfully without needing to "revert the reversion"
(see the revert-a-faulty-merge How-To[1] for details).
MERGE STRATEGIES
The merge mechanism (git merge and git pull commands) allows the
backend merge strategies to be chosen with -s option. Some strategies
can also take their own options, which can be passed by giving
-X<option> arguments to git merge and/or git pull.
resolve
This can only resolve two heads (i.e. the current branch and
another branch you pulled from) using a 3-way merge algorithm. It
tries to carefully detect criss-cross merge ambiguities and is
considered generally safe and fast.
recursive
This can only resolve two heads using a 3-way merge algorithm. When
there is more than one common ancestor that can be used for 3-way
merge, it creates a merged tree of the common ancestors and uses
that as the reference tree for the 3-way merge. This has been
reported to result in fewer merge conflicts without causing
mismerges by tests done on actual merge commits taken from Linux
2.6 kernel development history. Additionally this can detect and
handle merges involving renames. This is the default merge strategy
when pulling or merging one branch.
The recursive strategy can take the following options:
ours
This option forces conflicting hunks to be auto-resolved
cleanly by favoring our version. Changes from the other tree
that do not conflict with our side are reflected to the merge
result. For a binary file, the entire contents are taken from
our side.
This should not be confused with the ours merge strategy, which
does not even look at what the other tree contains at all. It
discards everything the other tree did, declaring our history
contains all that happened in it.
theirs
This is the opposite of ours.
patience
With this option, merge-recursive spends a little extra time to
avoid mismerges that sometimes occur due to unimportant
matching lines (e.g., braces from distinct functions). Use this
when the branches to be merged have diverged wildly. See also
git-diff(1) --patience.
diff-algorithm=[patience|minimal|histogram|myers]
Tells merge-recursive to use a different diff algorithm, which
can help avoid mismerges that occur due to unimportant matching
lines (such as braces from distinct functions). See also git-
diff(1) --diff-algorithm.
ignore-space-change, ignore-all-space, ignore-space-at-eol
Treats lines with the indicated type of whitespace change as
unchanged for the sake of a three-way merge. Whitespace changes
mixed with other changes to a line are not ignored. See also
git-diff(1) -b, -w, and --ignore-space-at-eol.
* If their version only introduces whitespace changes to a
line, our version is used;
* If our version introduces whitespace changes but their
version includes a substantial change, their version is
used;
* Otherwise, the merge proceeds in the usual way.
renormalize
This runs a virtual check-out and check-in of all three stages
of a file when resolving a three-way merge. This option is
meant to be used when merging branches with different clean
filters or end-of-line normalization rules. See "Merging
branches with differing checkin/checkout attributes" in
gitattributes(5) for details.
no-renormalize
Disables the renormalize option. This overrides the
merge.renormalize configuration variable.
no-renames
Turn off rename detection. See also git-diff(1) --no-renames.
find-renames[=<n>]
Turn on rename detection, optionally setting the similarity
threshold. This is the default. See also git-diff(1)
--find-renames.
rename-threshold=<n>
Deprecated synonym for find-renames=<n>.
subtree[=<path>]
This option is a more advanced form of subtree strategy, where
the strategy makes a guess on how two trees must be shifted to
match with each other when merging. Instead, the specified path
is prefixed (or stripped from the beginning) to make the shape
of two trees to match.
octopus
This resolves cases with more than two heads, but refuses to do a
complex merge that needs manual resolution. It is primarily meant
to be used for bundling topic branch heads together. This is the
default merge strategy when pulling or merging more than one
branch.
ours
This resolves any number of heads, but the resulting tree of the
merge is always that of the current branch head, effectively
ignoring all changes from all other branches. It is meant to be
used to supersede old development history of side branches. Note
that this is different from the -Xours option to the recursive
merge strategy.
subtree
This is a modified recursive strategy. When merging trees A and B,
if B corresponds to a subtree of A, B is first adjusted to match
the tree structure of A, instead of reading the trees at the same
level. This adjustment is also done to the common ancestor tree.
With the strategies that use 3-way merge (including the default,
recursive), if a change is made on both branches, but later reverted on
one of the branches, that change will be present in the merged result;
some people find this behavior confusing. It occurs because only the
heads and the merge base are considered when performing a merge, not
the individual commits. The merge algorithm therefore considers the
reverted change as no change at all, and substitutes the changed
version instead.
NOTES
You should understand the implications of using git rebase on a repository that you share. See also RECOVERING FROM UPSTREAM REBASE below. When the git-rebase command is run, it will first execute a "pre-rebase" hook if one exists. You can use this hook to do sanity checks and reject the rebase if it isn't appropriate. Please see the template pre-rebase hook script for an example. Upon completion, <branch> will be the current branch.
INTERACTIVE MODE
Rebasing interactively means that you have a chance to edit the commits
which are rebased. You can reorder the commits, and you can remove them
(weeding out bad or otherwise unwanted patches).
The interactive mode is meant for this type of workflow:
1. have a wonderful idea
2. hack on the code
3. prepare a series for submission
4. submit
where point 2. consists of several instances of
a) regular use
1. finish something worthy of a commit
2. commit
b) independent fixup
1. realize that something does not work
2. fix that
3. commit it
Sometimes the thing fixed in b.2. cannot be amended to the not-quite
perfect commit it fixes, because that commit is buried deeply in a
patch series. That is exactly what interactive rebase is for: use it
after plenty of "a"s and "b"s, by rearranging and editing commits, and
squashing multiple commits into one.
Start it with the last commit you want to retain as-is:
git rebase -i <after-this-commit>
An editor will be fired up with all the commits in your current branch
(ignoring merge commits), which come after the given commit. You can
reorder the commits in this list to your heart's content, and you can
remove them. The list looks more or less like this:
pick deadbee The oneline of this commit
pick fa1afe1 The oneline of the next commit
...
The oneline descriptions are purely for your pleasure; git rebase will
not look at them but at the commit names ("deadbee" and "fa1afe1" in
this example), so do not delete or edit the names.
By replacing the command "pick" with the command "edit", you can tell
git rebase to stop after applying that commit, so that you can edit the
files and/or the commit message, amend the commit, and continue
rebasing.
If you just want to edit the commit message for a commit, replace the
command "pick" with the command "reword".
To drop a commit, replace the command "pick" with "drop", or just
delete the matching line.
If you want to fold two or more commits into one, replace the command
"pick" for the second and subsequent commits with "squash" or "fixup".
If the commits had different authors, the folded commit will be
attributed to the author of the first commit. The suggested commit
message for the folded commit is the concatenation of the commit
messages of the first commit and of those with the "squash" command,
but omits the commit messages of commits with the "fixup" command.
git rebase will stop when "pick" has been replaced with "edit" or when
a command fails due to merge errors. When you are done editing and/or
resolving conflicts you can continue with git rebase --continue.
For example, if you want to reorder the last 5 commits, such that what
was HEAD~4 becomes the new HEAD. To achieve that, you would call git
rebase like this:
$ git rebase -i HEAD~5
And move the first patch to the end of the list.
You might want to preserve merges, if you have a history like this:
X
\
A---M---B
/
---o---O---P---Q
Suppose you want to rebase the side branch starting at "A" to "Q". Make
sure that the current HEAD is "B", and call
$ git rebase -i -p --onto Q O
Reordering and editing commits usually creates untested intermediate
steps. You may want to check that your history editing did not break
anything by running a test, or at least recompiling at intermediate
points in history by using the "exec" command (shortcut "x"). You may
do so by creating a todo list like this one:
pick deadbee Implement feature XXX
fixup f1a5c00 Fix to feature XXX
exec make
pick c0ffeee The oneline of the next commit
edit deadbab The oneline of the commit after
exec cd subdir; make test
...
The interactive rebase will stop when a command fails (i.e. exits with
non-0 status) to give you an opportunity to fix the problem. You can
continue with git rebase --continue.
The "exec" command launches the command in a shell (the one specified
in $SHELL, or the default shell if $SHELL is not set), so you can use
shell features (like "cd", ">", ";" ...). The command is run from the
root of the working tree.
$ git rebase -i --exec "make test"
This command lets you check that intermediate commits are compilable.
The todo list becomes like that:
pick 5928aea one
exec make test
pick 04d0fda two
exec make test
pick ba46169 three
exec make test
pick f4593f9 four
exec make test
SPLITTING COMMITS
In interactive mode, you can mark commits with the action "edit".
However, this does not necessarily mean that git rebase expects the
result of this edit to be exactly one commit. Indeed, you can undo the
commit, or you can add other commits. This can be used to split a
commit into two:
* Start an interactive rebase with git rebase -i <commit>^, where
<commit> is the commit you want to split. In fact, any commit range
will do, as long as it contains that commit.
* Mark the commit you want to split with the action "edit".
* When it comes to editing that commit, execute git reset HEAD^. The
effect is that the HEAD is rewound by one, and the index follows
suit. However, the working tree stays the same.
* Now add the changes to the index that you want to have in the first
commit. You can use git add (possibly interactively) or git gui (or
both) to do that.
* Commit the now-current index with whatever commit message is
appropriate now.
* Repeat the last two steps until your working tree is clean.
* Continue the rebase with git rebase --continue.
If you are not absolutely sure that the intermediate revisions are
consistent (they compile, pass the testsuite, etc.) you should use git
stash to stash away the not-yet-committed changes after each commit,
test, and amend the commit if fixes are necessary.
RECOVERING FROM UPSTREAM REBASE
Rebasing (or any other form of rewriting) a branch that others have
based work on is a bad idea: anyone downstream of it is forced to
manually fix their history. This section explains how to do the fix
from the downstream's point of view. The real fix, however, would be to
avoid rebasing the upstream in the first place.
To illustrate, suppose you are in a situation where someone develops a
subsystem branch, and you are working on a topic that is dependent on
this subsystem. You might end up with a history like the following:
o---o---o---o---o---o---o---o---o master
\
o---o---o---o---o subsystem
\
*---*---* topic
If subsystem is rebased against master, the following happens:
o---o---o---o---o---o---o---o master
\ \
o---o---o---o---o o'--o'--o'--o'--o' subsystem
\
*---*---* topic
If you now continue development as usual, and eventually merge topic to
subsystem, the commits from subsystem will remain duplicated forever:
o---o---o---o---o---o---o---o master
\ \
o---o---o---o---o o'--o'--o'--o'--o'--M subsystem
\ /
*---*---*-..........-*--* topic
Such duplicates are generally frowned upon because they clutter up
history, making it harder to follow. To clean things up, you need to
transplant the commits on topic to the new subsystem tip, i.e., rebase
topic. This becomes a ripple effect: anyone downstream from topic is
forced to rebase too, and so on!
There are two kinds of fixes, discussed in the following subsections:
Easy case: The changes are literally the same.
This happens if the subsystem rebase was a simple rebase and had no
conflicts.
Hard case: The changes are not the same.
This happens if the subsystem rebase had conflicts, or used
--interactive to omit, edit, squash, or fixup commits; or if the
upstream used one of commit --amend, reset, or filter-branch.
The easy case
Only works if the changes (patch IDs based on the diff contents) on
subsystem are literally the same before and after the rebase subsystem
did.
In that case, the fix is easy because git rebase knows to skip changes
that are already present in the new upstream. So if you say (assuming
you're on topic)
$ git rebase subsystem
you will end up with the fixed history
o---o---o---o---o---o---o---o master
\
o'--o'--o'--o'--o' subsystem
\
*---*---* topic
The hard case
Things get more complicated if the subsystem changes do not exactly
correspond to the ones before the rebase.
Note
While an "easy case recovery" sometimes appears to be successful
even in the hard case, it may have unintended consequences. For
example, a commit that was removed via git rebase --interactive
will be resurrected!
The idea is to manually tell git rebase "where the old subsystem ended
and your topic began", that is, what the old merge-base between them
was. You will have to find a way to name the last commit of the old
subsystem, for example:
* With the subsystem reflog: after git fetch, the old tip of
subsystem is at subsystem@{1}. Subsequent fetches will increase the
number. (See git-reflog(1).)
* Relative to the tip of topic: knowing that your topic has three
commits, the old tip of subsystem must be topic~3.
You can then transplant the old subsystem..topic to the new tip by
saying (for the reflog case, and assuming you are on topic already):
$ git rebase --onto subsystem subsystem@{1}
The ripple effect of a "hard case" recovery is especially bad: everyone
downstream from topic will now have to perform a "hard case" recovery
too!
BUGS
The todo list presented by --preserve-merges --interactive does not
represent the topology of the revision graph. Editing commits and
rewording their commit messages should work fine, but attempts to
reorder commits tend to produce counterintuitive results.
For example, an attempt to rearrange
1 --- 2 --- 3 --- 4 --- 5
to
1 --- 2 --- 4 --- 3 --- 5
by moving the "pick 4" line will result in the following history:
3
/
1 --- 2 --- 4 --- 5
GIT
Part of the git(1) suite
NOTES
1. revert-a-faulty-merge How-To
file:///usr/share/doc/git/html/howto/revert-a-faulty-merge.html
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Free Software
Free Software provides computer programs and capabilities at no cost but more importantly, it provides the freedom to run, edit, contribute to, and share the software. The importance of free software is a matter of access, not price. Software at no cost is a benefit but ownership rights to the software and source code is far more significant.
Free Office Software - The Libre Office suite provides top desktop productivity tools for free. This includes, a word processor, spreadsheet, presentation engine, drawing and flowcharting, database and math applications. Libre Office is available for Linux or Windows.
Free Books
The Free Books Library is a collection of thousands of the most popular public domain books in an online readable format. The collection includes great classical literature and more recent works where the U.S. copyright has expired. These books are yours to read and use without restrictions.
Source Code - Want to change a program or know how it works? Open Source provides the source code for its programs so that anyone can use, modify or learn how to write those programs themselves. Visit the GNU source code repositories to download the source.
Education
Study at Harvard, Stanford or MIT - Open edX provides free online courses from Harvard, MIT, Columbia, UC Berkeley and other top Universities. Hundreds of courses for almost all major subjects and course levels. Open edx also offers some paid courses and selected certifications.
Linux Manual Pages - A man or manual page is a form of software documentation found on Linux/Unix operating systems. Topics covered include computer programs (including library and system calls), formal standards and conventions, and even abstract concepts.
