# Basic check
shellcheck script.sh
 
# With severity filter
shellcheck --severity=warning script.sh
 
# Specific shell dialect
shellcheck --shell=bash script.sh
 
# Output formats
shellcheck --format=json script.sh
shellcheck --format=gcc script.sh
 
# Check multiple files
shellcheck *.sh

# Bad
rm $file
echo $var
 
# Good
rm "$file"
echo "$var"

# Bad
rm $(find . -name "*.tmp")
 
# Good
rm "$(find . -name "*.tmp")"
# Or for multiple results:
find . -name "*.tmp" -delete

# Bad
date=`date`
 
# Good
date=$(date)

# Bad
cd /some/dir
do_something
 
# Good
cd /some/dir || exit 1
do_something

# Bad
local var=$(command)
 
# Good
local var
var=$(command)

# Bad
read line
 
# Good
read -r line

# Check if it's exported or used in eval/source
# Or prefix with _ to indicate intentionally unused
_unused_var="value"

# Disable for next line
# shellcheck disable=SC2086
echo $unquoted_var
 
# Disable for entire file (at top)
# shellcheck disable=SC2034,SC2086
 
# Disable for block
# shellcheck disable=SC2086
{
    echo $var1
    echo $var2
}

## Issues Found
 
### Errors (must fix)
- Line 10, SC2086: Double quote to prevent globbing and word splitting
 
### Warnings (should fix)
- Line 15, SC2155: Declare and assign separately to avoid masking return values
 
### Suggestions
- Line 20, SC2034: UNUSED_VAR appears unused (verify or prefix with _)
 
## Fixed Code
[Show corrected version]