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Updated SC2018 (markdown)

koalaman
2017-06-18 15:18:02 -07:00
parent ce24bf631f
commit 5f61ad8702
1 changed files with 21 additions and 3 deletions
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24
SC2018.md

@@ -3,11 +3,29 @@
### Problematic code:
```sh
PLATFORM="$(uname -s | tr 'a-z')"
PLATFORM="$(uname -s | tr 'A-Z' 'a-z')"
```
### Correct code:
```sh
PLATFORM="$(uname -s | tr '[:lower:]')"
```
PLATFORM="$(uname -s | tr '[:upper:]' '[:lower:]')"
```
### Rationale:
`A-Z` and `a-z` are commonly intended to mean "all uppercase" and "all lowercase letters" respectively. This ignores accented characters in English, and foreign characters in other languages:
$ tr 'a-z' 'A-Z' <<< "My fiancée ordered a piña colada."
MY FIANCéE ORDERED A PIñA COLADA.
Instead, you can use `[:lower:]` and `[:upper:]` to explicitly specify case:
$ tr '[:lower:]' '[:upper:]' <<< "My fiancée ordered a piña colada."
MY FIANCÉE ORDERED A PIÑA COLADA.
### Exceptions:
If you don't want `a-z` to match `é` or `A-Z` to match `Ñ`, you can ignore this message.
Note that the examples used here are multibyte characters in UTF-8. Many implementations (including GNU) fails to deal with them.