git-check-ref-format(1)
NAME
git-check-ref-format - Ensures that a reference name is well formed
SYNOPSIS
git check-ref-format [--normalize]
[--[no-]allow-onelevel] [--refspec-pattern]
<refname>
git check-ref-format --branch <branchname-shorthand>
DESCRIPTION
Checks if a given refname is acceptable, and exits with a non-zero
status if it is not.
A reference is used in Git to specify branches and tags. A branch head
is stored in the refs/heads hierarchy, while a tag is stored in the
refs/tags hierarchy of the ref namespace (typically in
$GIT_DIR/refs/heads and $GIT_DIR/refs/tags directories or, as entries
in file $GIT_DIR/packed-refs if refs are packed by git gc).
Git imposes the following rules on how references are named:
1. They can include slash / for hierarchical (directory) grouping, but
no slash-separated component can begin with a dot . or end with
the sequence .lock.
2. They must contain at least one /. This enforces the presence of a
category like heads/, tags/ etc. but the actual names are not
restricted. If the --allow-onelevel option is used, this rule is
waived.
3. They cannot have two consecutive dots .. anywhere.
4. They cannot have ASCII control characters (i.e. bytes whose values
are lower than \040, or \177 DEL), space, tilde ~, caret ^, or
colon : anywhere.
5. They cannot have question-mark ?, asterisk *, or open bracket [
anywhere. See the --refspec-pattern option below for an exception
to this rule.
6. They cannot begin or end with a slash / or contain multiple
consecutive slashes (see the --normalize option below for an
exception to this rule)
7. They cannot end with a dot ..
8. They cannot contain a sequence @{.
9. They cannot be the single character @.
10. They cannot contain a \.
These rules make it easy for shell script based tools to parse
reference names, pathname expansion by the shell when a reference name
is used unquoted (by mistake), and also avoid ambiguities in certain
reference name expressions (see gitrevisions(7)):
1. A double-dot .. is often used as in ref1..ref2, and in some
contexts this notation means ^ref1 ref2 (i.e. not in ref1 and in
ref2).
2. A tilde ~ and caret ^ are used to introduce the postfix nth parent
and peel onion operation.
3. A colon : is used as in srcref:dstref to mean "use srcref's value
and store it in dstref" in fetch and push operations. It may also
be used to select a specific object such as with git cat-file: "git
cat-file blob v1.3.3:refs.c".
4. at-open-brace @{ is used as a notation to access a reflog entry.
With the --branch option, it expands the "previous branch syntax"
@{-n}. For example, @{-1} is a way to refer the last branch you were
on. This option should be used by porcelains to accept this syntax
anywhere a branch name is expected, so they can act as if you typed the
branch name.
OPTIONS
--[no-]allow-onelevel
Controls whether one-level refnames are accepted (i.e., refnames
that do not contain multiple /-separated components). The default
is --no-allow-onelevel.
--refspec-pattern
Interpret <refname> as a reference name pattern for a refspec (as
used with remote repositories). If this option is enabled,
<refname> is allowed to contain a single * in the refspec (e.g.,
foo/bar*/baz or foo/bar*baz/ but not foo/bar*/baz*).
--normalize
Normalize refname by removing any leading slash (/) characters and
collapsing runs of adjacent slashes between name components into a
single slash. Iff the normalized refname is valid then print it to
standard output and exit with a status of 0. (--print is a
deprecated way to spell --normalize.)
EXAMPLES
* Print the name of the previous branch:
$ git check-ref-format --branch @{-1}
* Determine the reference name to use for a new branch:
$ ref=$(git check-ref-format --normalize "refs/heads/$newbranch")||
{ echo "we do not like '$newbranch' as a branch name." >&2 ; exit 1 ; }
GIT
Part of the git(1) suite
Opportunity
Personal Opportunity - Free software gives you access to billions of dollars of software at no cost. Use this software for your business, personal use or to develop a profitable skill. Access to source code provides access to a level of capabilities/information that companies protect though copyrights. Open source is a core component of the Internet and it is available to you. Leverage the billions of dollars in resources and capabilities to build a career, establish a business or change the world. The potential is endless for those who understand the opportunity.
Business Opportunity - Goldman Sachs, IBM and countless large corporations are leveraging open source to reduce costs, develop products and increase their bottom lines. Learn what these companies know about open source and how open source can give you the advantage.
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.
