mirror of https://github.com/CrimsonTome/tldr.git
29 lines
776 B
Markdown
29 lines
776 B
Markdown
# if
|
|
|
|
> Simple shell conditional.
|
|
> See also: `test`, `[`.
|
|
|
|
- Execute two different commands based on a condition:
|
|
|
|
`if {{command}}; then {{echo "true"}}; else {{echo "false"}}; fi`
|
|
|
|
- Check if a variable is defined:
|
|
|
|
`if [[ -n "{{$VARIABLE}}" ]]; then {{echo "defined"}}; else {{echo "not defined"}}; fi`
|
|
|
|
- Check if a file exists:
|
|
|
|
`if [[ -f "{{path/to/file}}" ]]; then {{echo "true"}}; else {{echo "false"}}; fi`
|
|
|
|
- Check if a directory exists:
|
|
|
|
`if [[ -d "{{path/to/directory}}" ]]; then {{echo "true"}}; else {{echo "false"}}; fi`
|
|
|
|
- Check if a file or directory exists:
|
|
|
|
`if [[ -e "{{path/to/file_or_directory}}" ]]; then {{echo "true"}}; else {{echo "false"}}; fi`
|
|
|
|
- List all possible conditions (`test` is an alias to `[`; both are commonly used with `if`):
|
|
|
|
`man [`
|