Concept: Pipelines and Command Lists #714
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| The pipe symbol (`|`) connects the output of one command to the input of another. | ||
| `cut` reads the output of `cat`, and `sort` reads the output of `cut`. |
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Do you want to take a step back and mention how many commands read from STDIN (and/or a file) and write to STDOUT? Introduce STDIN/STDOUT?
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Right, I'll do a "sneak preview" of I/O, with a promise of more to come in a later concept.
Co-authored-by: Isaac Good <[email protected]>
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@IsaacG can I get your opinion on the I/O blurb please? |
concepts/pipelines/about.md
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| * A process can emit _error output_ on "stderr". | ||
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| The `tr` command is a very pure example of this. | ||
| All it does is read text from its stdin, perform character transliterations, and print the resulting text to stdout. |
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We quote stdout in prior references, should we keep it consistent. It is a literal in the language as well. If we are generally talking about standard out and standard in, then expressing it in that way may be useful. Similar to standard input/output or I/O or something other than stdio as plain text, rather than somehow marked as the "thing" we are referencing in terms of the language, rather than an idea. Consistency is really what my comment is about, not only this line and close to this line, but throughout this document, at least.
concepts/pipelines/about.md
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| ### Uses of Command Lists | ||
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| Here are a couple of examples where command lists can simplify bash code. |
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| Here are a couple of examples where command lists can simplify bash code. | |
| Here are a couple of examples where command lists can simplify the code. |
Because the context is Bash, we can likely reference it this way.
concepts/pipelines/about.md
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| #### Reading blocks of lines from a file | ||
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| Suppose you have a data file that represents points of a triangle as the length of the three sides but each on a separate line. |
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| Suppose you have a data file that represents points of a triangle as the length of the three sides but each on a separate line. | |
| Suppose you have a data file that represents the sides of a triangle as the length of the three sides but each on a separate line. |
It still seems a bit clunky or something with the change, but points never have a length, so we must be talking about something with a length, and that would be the sides.
concepts/pipelines/about.md
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| assert(x == 5, "x must be 5"); | ||
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| We can use an OR operator in bash to simulate that function: |
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| We can use an OR operator in bash to simulate that function: | |
| We can use an OR operator in Bbash to simulate that function: |
I believe Bash as a name of the scripting language should be capitalized, otherwise it appears as though we are talking about the executable, rather than the language.
concepts/pipelines/introduction.md
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| ## I/O | ||
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| Before we start, a quick intro to input/output. |
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| Before we start, a quick intro to input/output. | |
| Before we start, a quick introduction to input/output, pretty commonly referenced as "I/O". |
concepts/pipelines/introduction.md
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| * By default, each command in a pipeline runs in a separate subshell. | ||
| (A subshell is a child process that is a copy of the currently running shell.) | ||
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| * All the commands in a subshell execute in parallel. |
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Is this always the case? Should we state that Bash is designed so that if it can, subshells are executed in parallel.
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Oops, all the commands in a pipeline execute in parallel.
I can't find where in the manual this is stated, although I believe it to be true. I can just remove it.
concepts/pipelines/introduction.md
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| #### Reading blocks of lines from a file | ||
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| Suppose you have a data file that represents points of a triangle as the length of the three sides but each on a separate line. |
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As in the other file, I believe points by definition have no length, nor size.
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