The Singularity command
Singularity uses a primary command wrapper called singularity. When you run singularity without any options or arguments it will dump the high level usage syntax.
The general usage form is:
$ singularity (opts1) [subcommand] (opts2) ...
If you type singularity without any arguments, you will see a high level help for all arguments:
USAGE: singularity [global options...] <command> [command options...] ...
GLOBAL OPTIONS:
-d --debug Print debugging information
-h --help Display usage summary
-q --quiet Only print errors
--version Show application version
-v --verbose Increase verbosity +1
-x --sh-debug Print shell wrapper debugging information
GENERAL COMMANDS:
help Show additional help for a command
CONTAINER USAGE COMMANDS:
exec Execute a command within container
run Launch a runscript within container
shell Run a Bourne shell within container
test Execute any test code defined within container
CONTAINER USAGE OPTIONS:
-H --home Specify $HOME to mount
CONTAINER MANAGEMENT COMMANDS (requires root):
bootstrap Bootstrap a new Singularity image from scratch
copy Copy files from your host into the container
create Create a new container image
expand Grow the container image
export Export the contents of a container via a tar pipe
import Import/add container contents via a tar pipe
mount Mount a Singularity container image
CONTAINER REGISTRY COMMANDS:
pull pull a Singularity Hub container to $PWD
For any additional help or support visit the Singularity
website: http://singularity.lbl.gov/
Options and argument processing
Because of the nature of how Singularity cascades commands and sub-commands, argument processing is done with a mandatory order. This means that where you place arguments is important! In the above usage example, opts1 are the global Singularity run-time options. These options are always applicable no matter what subcommand you select (e.g. --verbose or --debug). But subcommand specific options must be passed after the relevant subcommand.
To further clarify this example, the exec Singularity subcommand will execute a program within the container and pass the arguments passed to the program. So to mitigate any argument clashes, Singularity must not interpret or interfere with any of the command arguments or options that are not relevant for that particular function.
Singularity Help
Singularity comes with some internal documentation by using the help subcommand followed by the subcommand you want more information about. For example:
$ singularity help create
USAGE: singularity (options) create [command] (options)
Create a new Singularity formatted blank image.
OPTIONS:
-s/--size Specify a size for an operation (default 1GB)
EXAMPLES:
$ sudo singularity create /tmp/Debian.img
$ sudo singularity create -s 4096 /tmp/Debian.img