Updated SC1138 (markdown)

Rushen Wang
2024-09-12 09:57:35 +08:00
parent 702f6917bf
commit 659bfd31dc

@@ -1,30 +1,19 @@
## Shells are space sensitive. Use `< <(cmd)`, not `<< (cmd)`.
## Remove spaces between (( in arithmetic for loop.
### Problematic code:
```sh
while read -r line
do
echo "You said: $line"
done <<(cmd)
for( (i=0; i<10; i++) ); do echo $i; done
```
### Correct code:
```sh
while read -r line
do
echo "You said: $line"
done < <(cmd)
for((i=0; i<10; i++)); do echo $i; done
```
### Rationale:
When redirecting `<` from a process substitution `<(cmd)`, make sure there is a space between the two `<` characters as shown in the example.
With a space `cmd1 < <(cmd2)`, is correctly interpreted as "run cmd1, reading stdin from cmd2, without forking for a pipeline".
Without a space, `<<` is incorrectly considered a here document, and `(cmd2)` is an invalid delimiter token.
ShellCheck finds arithmetic for ((;;)) expressions where (( or )) are intervening with spaces
### Exceptions: