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https://github.com/jbranchaud/til
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jbranchaud
65 lines
1.6 KiB
Markdown
65 lines
1.6 KiB
Markdown
# Reverse Each Line Of A File
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The [`rev` command](https://man7.org/linux/man-pages/man1/rev.1.html) can be
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used to reverse each line in a file. Every line is left where it is relative to
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other lines, but the contents of each line is reversed.
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So a file that contains the following text:
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```bash
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❯ cat stuff.md
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Three
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Two
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One
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go racecar go
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```
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can be piped to `rev` to get the following output:
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```bash
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❯ rev stuff.md
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eerhT
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owT
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enO
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og racecar og
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```
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This is an odd utility that doesn't have too much use that I can imagine. After
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a brief chat with Claude where I asked for some practical use cases, the one
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that stood out the most to me is to reverse a list of filenames, sort them, and
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then reverse them again (putting them back in readable order). This can shuffle
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filenames with similar endings near each other like source and test files.
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Here is a list of files for me [`py-vmt`
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project](https://github.com/jbranchaud/py-vmt):
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```bash
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❯ fd -t f .
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README.md
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pyproject.toml
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src/py_vmt/__init__.py
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src/py_vmt/cli.py
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src/py_vmt/session.py
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src/py_vmt/time_helpers.py
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tests/src/py_vmt/test_cli.py
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tests/src/py_vmt/test_session.py
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```
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Now I can pipe the output of that `fd` command through `rev | sort | rev` to get
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my files organized in a different way.
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```bash
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❯ fd -t f . | rev | sort | rev
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README.md
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pyproject.toml
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src/py_vmt/__init__.py
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tests/src/py_vmt/test_cli.py
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src/py_vmt/cli.py
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tests/src/py_vmt/test_session.py
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src/py_vmt/session.py
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src/py_vmt/time_helpers.py
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```
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Again the value of doing something like this is a bit tenuous. At the very least
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it is fun to know about.
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