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Updated SC2051 (markdown)

koalaman
2018-01-25 19:29:07 -08:00
parent d0ef7a4c3c
commit d7a155e77d
1 changed files with 8 additions and 1 deletions
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SC2051.md

@@ -24,18 +24,25 @@ In Bash, brace expansion happens before variable expansion. This means that brac
For integers, use an arithmetic for loop instead. For zero-padded numbers or letters, use of eval may be warranted: For integers, use an arithmetic for loop instead. For zero-padded numbers or letters, use of eval may be warranted:
```bash
from="a" to="m" from="a" to="m"
for c in $(eval "echo {$from..$to}"); do echo "$c"; done for c in $(eval "echo {$from..$to}"); do echo "$c"; done
```
or more carefully (if `from`/`to` could be user input, or if the brace expansion could have spaces): or more carefully (if `from`/`to` could be user input, or if the brace expansion could have spaces):
```bash
from="a" to="m" from="a" to="m"
while IFS= read -d '' -r c while IFS= read -d '' -r c
do do
echo "Read $c" echo "Read $c"
done < <(eval "printf '%s\0' $(printf "{%q..%q}.jpg" "$from" "$to")") done < <(eval "printf '%s\0' $(printf "{%q..%q}.jpg" "$from" "$to")")
```
### Exceptions ### Exceptions
None (if you're writing for e.g. zsh, make sure the shebang indicates this so shellcheck won't warn) None (if you're writing for e.g. zsh, make sure the shebang indicates this so shellcheck won't warn)
### Related Resources:
* [StackOverflow: Variables in bash seq replacement ({1..10})](https://stackoverflow.com/questions/169511/how-do-i-iterate-over-a-range-of-numbers-defined-by-variables-in-bash)