2022-06-28 18:39:45 +02:00
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---
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2022-07-07 08:32:34 +02:00
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title: 'Useful Commands'
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2022-11-19 15:25:20 +01:00
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visible: true
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2022-06-28 18:39:45 +02:00
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---
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[toc]
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## Imagemagick
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### Splitting PDF files
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`$ convert -density 600 (input.pdf) -crop 50x100% +repage (out.pdf)`
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```
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-density: adjusts the quality of the resulting pdf. Higher values look better, but take longer to process
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-crop 50x100%: this splits the pdf into "left" and "right". 100x50% would split into "top" and "bottom"
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2022-07-07 08:35:48 +02:00
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```
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## Find
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### Change filtered permissions
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Using find with its `exec` switch one can set different permissions based on the usual find filters.
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One example would be only changing file or directory permissions.
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`$ find (directory) -type f -exec chmod 744 {} +`
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Replacing `-type f` with `-type d` would execute the `chmod` for directories instead.
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2022-10-18 20:43:26 +02:00
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## Various
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### Overwrite disk with pseudorandom data
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Using openssl on CPUs with AES acceleration one can create pseudorandom data with high speeds.
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Much faster than `/dev/urandom` at least
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`# openssl enc -aes-128-ctr -md sha512 -pbkdf2 -nosalt -pass file:/dev/urandom < /dev/zero | pv > (target disk)`
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Around 2GiB/s on my Ryzen 7 1700x if output to `/dev/null`
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2022-10-23 20:44:13 +02:00
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### Formatted csv in terminal
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2022-10-23 20:51:00 +02:00
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> [From Pretty CSV viewing on the Command Line](https://www.stefaanlippens.net/pretty-csv.html)
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2022-10-23 20:44:13 +02:00
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`$ column -t -s, < (file.csv)`
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