53 lines
2.0 KiB
Markdown
53 lines
2.0 KiB
Markdown
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---
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title: GAWK
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TARGET DECK: Obsidian::STEM
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FILE TAGS: linux::cli gawk
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tags:
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- gawk
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---
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## Variables
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Variables are defined like `var=val`. They can be specified in two different places:
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1. Via the `-v` command line flag. Using this allows accessing the variable value from within a `BEGIN` rule.
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2. In the file list. Using this allows accessing the variable value in all subsequent file processing.
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%%ANKI
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Basic
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Where in an `awk` invocation can variables be assigned?
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Back: As a `-v` argument or in the file list.
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Reference: Robbins, Arnold D. “GAWK: Effective AWK Programming,” October 2023. [https://www.gnu.org/software/gawk/manual/gawk.pdf](https://www.gnu.org/software/gawk/manual/gawk.pdf)
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<!--ID: 1706885111450-->
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END%%
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%%ANKI
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Basic
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The `-v` flag was introduced to accommodate what functionality?
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Back: Accessing variables from a `BEGIN` rule.
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Reference: Robbins, Arnold D. “GAWK: Effective AWK Programming,” October 2023. [https://www.gnu.org/software/gawk/manual/gawk.pdf](https://www.gnu.org/software/gawk/manual/gawk.pdf)
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<!--ID: 1706885111454-->
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END%%
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%%ANKI
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Basic
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Describe what the following command does in in a single sentence:
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```bash
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$ awk 'program' pass=1 data pass=2 data
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```
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Back: Evaluates `'program'` against the `data` file twice with a different value of `pass` on each run.
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Reference: Robbins, Arnold D. “GAWK: Effective AWK Programming,” October 2023. [https://www.gnu.org/software/gawk/manual/gawk.pdf](https://www.gnu.org/software/gawk/manual/gawk.pdf)
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<!--ID: 1706885111457-->
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END%%
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%%ANKI
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Basic
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How is `stdin` specified in `awk`'s file list?
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Back: `-`
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Reference: Robbins, Arnold D. “GAWK: Effective AWK Programming,” October 2023. [https://www.gnu.org/software/gawk/manual/gawk.pdf](https://www.gnu.org/software/gawk/manual/gawk.pdf)
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<!--ID: 1706973587236-->
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END%%
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## References
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* Robbins, Arnold D. “GAWK: Effective AWK Programming,” October 2023. [https://www.gnu.org/software/gawk/manual/gawk.pdf](https://www.gnu.org/software/gawk/manual/gawk.pdf)
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