# Bash Tips

## prevent last false

function body should not end up with a ternary statement

### wrong last

Compound of 2 'false' statement returns false.

```bash
[[ : ]] && [[ : ]]
```

### right last

```bash
[[ : ]] && [[ : ]] || true
```

## arithmetic issue

last (++) statement does not complete successfully!

### wrong ++

```bash
count=0
(( ++count )) # ok 
(( ++count )) # last statement in function returns false
```

### right ++

```bash
count=0
count=$((count+1))
```

## properly grab $?

> prefer plain `command` rather than `! command`
> otherwise you will miss out the exit code

### wrong if

```bash
  if ! command; then
    local code=$?
    >&2 echo $code # => 0
  fi
```

### right if

```bash
  if command; then
    : # useful for preserving $?
  else
    local code=$?
    >&2 echo $code
  fi
```

## sudo -E or better source if already root

From within a miaou-bash script and in case sudo is required

1. prefer using source if already root
2. or force preserving the MIAOU_BASH_DIR environment variable with `sudo -E