Pdf 1.7 Reference

[Stetson Saenz]

Copyright1995-2018 by The Writing Lab & The OWL at Purdue and Purdue University. All rights reserved. This material may not be published, reproduced, broadcast, rewritten, or redistributed without permission. Use of this site constitutes acceptance of our terms and conditions of fair use.

This resourse, revised according to the 7th edition APA Publication Manual, offers basic guidelines for formatting the reference list at the end of a standard APA research paper. Most sources follow fairly straightforward rules. However, because sources obtained from academic journals carry special weight in research writing, these sources are subject to special rules. Thus, this page presents basic guidelines for citing academic journals separate from its "ordinary" basic guidelines. This distinction is made clear below.

Note: Because the information on this page pertains to virtually all citations, we've highlighted one important difference between APA 6 and APA 7 with an underlined note written in red. For more information, please consult the Publication Manual of the American Psychological Association, (7th ed.).

Your reference list should appear at the end of your paper. It provides the information necessary for a reader to locate and retrieve any source you cite in the body of the paper. Each source you cite in the paper must appear in your reference list; likewise, each entry in the reference list must be cited in your text.

Your references should begin on a new page separate from the text of the essay; label this page "References" in bold, centered at the top of the page (do NOT underline or use quotation marks for the title). All text should be double-spaced just like the rest of your essay.

Please note: While the APA manual provides examples of how to cite common types of sources, it does not cover all conceivable sources. If you must cite a source that APA does not address, the APA suggests finding an example that is similar to your source and using that format. For more information, see page 282 of the Publication Manual of the American Psychological Association, 7th ed.

Purdue OWL is a registered trademark. Copyright 2024 by The On-Campus Writing Lab & The OWL at Purdue and Purdue University. This material may not be published, reproduced, broadcast, rewritten, or redistributed without permission. This website collects and publishes the ideas of individuals who have contributed those ideas in their capacities as faculty-mentored student scholars. The materials collected here do not express the views of, or positions held by, Purdue University. Use of this site constitutes acceptance of our terms and conditions of fair use. Privacy policy.

Docker can build images automatically by reading the instructions from aDockerfile. A Dockerfile is a text document that contains all the commands auser could call on the command line to assemble an image. This page describesthe commands you can use in a Dockerfile.

Docker runs instructions in a Dockerfile in order. A Dockerfile mustbegin with a FROM instruction. This may be afterparserdirectives,comments, and globally scopedARGs. The FROM instruction specifies theparentimage from which you arebuilding. FROM may only be preceded by one or more ARG instructions, whichdeclare arguments that are used in FROM lines in the Dockerfile.

For backward compatibility, leading whitespace before comments (#) andinstructions (such as RUN) are ignored, but discouraged. Leading whitespaceis not preserved in these cases, and the following examples are thereforeequivalent:

Parser directives are optional, and affect the way in which subsequent linesin a Dockerfile are handled. Parser directives don't add layers to the build,and don't show up as build steps. Parser directives are written as aspecial type of comment in the form # directive=value. A single directivemay only be used once.

Once a comment, empty line or builder instruction has been processed, BuildKitno longer looks for parser directives. Instead it treats anything formattedas a parser directive as a comment and doesn't attempt to validate if it mightbe a parser directive. Therefore, all parser directives must be at thetop of a Dockerfile.

Parser directives aren't case-sensitive, but they're lowercase by convention.It's also conventional to include a blank line following any parser directives.Line continuation characters aren't supported in parser directives.

Use the syntax parser directive to declare the Dockerfile syntax version touse for the build. If unspecified, BuildKit uses a bundled version of theDockerfile frontend. Declaring a syntax version lets you automatically use thelatest Dockerfile version without having to upgrade BuildKit or Docker Engine,or even use a custom Dockerfile implementation.

The escape character is used both to escape characters in a line, and toescape a newline. This allows a Dockerfile instruction tospan multiple lines. Note that regardless of whether the escape parserdirective is included in a Dockerfile, escaping is not performed ina RUN command, except at the end of a line.

Consider the following example which would fail in a non-obvious way onWindows. The second \ at the end of the second line would be interpreted as anescape for the newline, instead of a target of the escape from the first \.Similarly, the \ at the end of the third line would, assuming it was actuallyhandled as an instruction, cause it be treated as a line continuation. The resultof this Dockerfile is that second and third lines are considered a singleinstruction:

One solution to the above would be to use / as the target of both the COPYinstruction, and dir. However, this syntax is, at best, confusing as it is notnatural for paths on Windows, and at worst, error prone as not all commands onWindows support / as the path separator.

Environment variables (declared withthe ENV statement) can also beused in certain instructions as variables to be interpreted by theDockerfile. Escapes are also handled for including variable-like syntaxinto a statement literally.

You can also use environment variables with RUN, CMD, and ENTRYPOINTinstructions, but in those cases the variable substitution is handled by thecommand shell, not the builder. Note that instructions using the exec formdon't invoke a command shell automatically. SeeVariablesubstitution.

Environment variable substitution use the same value for each variablethroughout the entire instruction. Changing the value of a variable only takeseffect in subsequent instructions. Consider the following example:

The exec form makes it possible to avoid shell string munging, and to invokecommands using a specific command shell, or any other executable. It uses aJSON array syntax, where each element in the array is a command, flag, orargument.

Using the exec form doesn't automatically invoke a command shell. This meansthat normal shell processing, such as variable substitution, doesn't happen.For example, RUN [ "echo", "$HOME" ] won't handle variable substitution for$HOME.

If you want shell processing then either use the shell form or execute a shelldirectly with the exec form, for example: RUN [ "sh", "-c", "echo $HOME" ].When using the exec form and executing a shell directly, as in the case for theshell form, it's the shell that's doing the environment variable substitution,not the builder.

In exec form, you must escape backslashes. This is particularly relevant onWindows where the backslash is the path separator. The following line wouldotherwise be treated as shell form due to not being valid JSON, and fail in anunexpected way:

Unlike the exec form, instructions using the shell form always use a commandshell. The shell form doesn't use the JSON array format, instead it's a regularstring. The shell form string lets you escape newlines using theescapecharacter (backslash by default) to continue a single instructiononto the next line. This makes it easier to use with longer commands, becauseit lets you split them up into multiple lines. For example, consider these twolines:

The optional --platform flag can be used to specify the platform of the imagein case FROM references a multi-platform image. For example, linux/amd64,linux/arm64, or windows/amd64. By default, the target platform of the buildrequest is used. Global build arguments can be used in the value of this flag,for exampleautomatic platform ARGsallow you to force a stage to native build platform (--platform=$BUILDPLATFORM),and use it to cross-compile to the target platform inside the stage.

An ARG declared before a FROM is outside of a build stage, so itcan't be used in any instruction after a FROM. To use the default value ofan ARG declared before the first FROM use an ARG instruction withouta value inside of a build stage:

The cache for RUN instructions isn't invalidated automatically duringthe next build. The cache for an instruction likeRUN apt-get dist-upgrade -y will be reused during the next build. Thecache for RUN instructions can be invalidated by using the --no-cacheflag, for example docker build --no-cache.

Contents of the cache directories persists between builder invocations withoutinvalidating the instruction cache. Cache mounts should only be used for betterperformance. Your build should work with any contents of the cache directory asanother build may overwrite the files or GC may clean it if more storage spaceis needed.

Apt needs exclusive access to its data, so the caches use the optionsharing=locked, which will make sure multiple parallel builds usingthe same cache mount will wait for each other and not access the samecache files at the same time. You could also use sharing=private ifyou prefer to have each build create another cache directory in thiscase.

The use of --network=host is protected by the network.host entitlement,which needs to be enabled when starting the buildkitd daemon with--allow-insecure-entitlement network.host flag or inbuildkitd config,and for a build request with--allow network.host flag.

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