This topic discusses what to call the command-line elements that are
used in the gcloud
command-line tool and in Linux commands.
General guidance
When discussing commands and their constituent parts, follow this guidance:
- Avoid mapping nomenclature of the
gcloud
tool's commands to Linux commands. - Linux commands can be complicated. It's wise to describe what the entire command does rather than what its individual elements are called.
- For Linux commands or commands in the
gcloud
tool, ask yourself if the reader must know the name of the command-line element or if explaining the command is sufficient.
gcloud commands
gcloud GROUP | COMMAND [--account=ACCOUNT] [--configuration=CONFIGURATION] \ [--flatten=[KEY,...]][--format=FORMAT] [--help] [--project=PROJECT_ID] \ [--quiet, -q][--verbosity=VERBOSITY; default="warning"] [--version, -v] \ [-h] [--log-http][--trace-token=TRACE_TOKEN] [--no-user-output-enabled]
For the sake of accurate classification, the gcloud
tool's
syntax distinguishes between a command and a command group. In
docs, however, command-line contents are generally referred to as commands.
You can use commands (and groups) alone or with one or more flags. A flag is a Google Cloud Platform–specific term for any element other than the command or group name itself. A command or flag might also take an argument, for example, a region value.
Example command:
gcloud init
Example command with a flag:
gcloud init --skip-diagnostics
Example command with multiple elements:
gcloud ml-engine jobs submit training ${JOB_NAME} \ --package-path trainer \ --module-name trainer.task \ --staging-bucket gs://${BUCKET} \ --job-dir gs://${BUCKET}/${JOB_NAME} \ --runtime-version 1.2 \ --region us-central1 \ --config config/config.yaml \ -- \ --data_dir gs://${BUCKET}/data \ --output_dir gs://${BUCKET}/${JOB_NAME} \ --train_steps 10000
Where:
ml-engine
is agcloud
command group.jobs
is anml-engine
command group.submit
is ajobs
command group.training
is asubmit
command.${JOB_NAME}
is an argument that refers to a variable calledJOB_NAME
that was set earlier.--package-path
is a flag.
In addition to the term flag, option is often used as a catchall term when you don't want to mire the reader in specialized nomenclature.
For more details, see the Cloud SDK: gcloud topic.
Linux commands
Where the gcloud
command-line tool uses the catchall terms
flag and option, Linux commands use options, parameters,
arguments, and a host of specialized syntax elements. Here's an
example:
find /usr/src/linux -follow -type f -name '*.[ch]' | xargs grep -iHn pcnet
Where:
find
is the command name./usr/src/linux
is an argument that specifies the path to look in. Easier to refer to as just a path.-follow
is an option. The-
(dash) is part of the option.-type
is an option with a value off
.-name
is an option with a value of'*.[ch]'
, where the asterisk (*
) is a metacharacter signifying a wildcard. Metacharacters are used in Linux shell commands for globbing, or filename expansion. In addition to the asterisk, metacharacters include the question mark (?) and caret (^).
The results of the first command are redirected using a pipe
(|)
to the xargs grep -iHn pcnet
command. Other
redirection symbols include >
, <
,
>>
, and <<
. Redirection means capturing
output from a file, command, program, script, or even code block within a script
and sending it as input to another file, command, program, or script.
Linux signals
Linux signals, or sigactions, require vocabulary choices that are generally discouraged elsewhere in documentation. We recommend using the terms discussed here only in the context of process control.
Signal | Description |
---|---|
SIGKILL |
Signal sent to kill a specified process, all members of a
specified process group, or all processes on the system. SIGKILL
cannot be caught, blocked, or ignored. Do not substitute cancel,
end, exit, quit, stop, or terminate. |
SIGTERM |
Signal sent as a request to terminate a process. Although
similar to SIGKILL , this signal gives the process a chance to
clean up any child processes that might be running. Do not substitute
cancel, end, exit, quit, or stop. |
SIGQUIT |
Signal sent from a keyboard to quit a process. Some processes can catch, block, or ignore a quit signal. Do not substitute cancel, end, exit, quit, or stop. |
SIGINT |
Signal sent to interrupt a process immediately. The default action of this signal is to terminate a process gracefully. It can be handled, ignored, or caught. It can be sent from a terminal—for example, when a user presses Control+C. Do not substitute suspend, end, exit, pause, or terminate. |
SIGPAUSE |
Signal that tells a process to pause, or sleep, until any signal is delivered that either terminates the process or invokes a signal-catching function. Do not substitute cancel or interrupt. |
SIGSUSPEND |
Signal sent to temporarily suspend execution of a process. Used to prevent delivery of a particular signal during the execution of a critical code section. Do not substitute pause or exit. |
SIGSTOP |
Signal sent to stop execution of a process for later
continuation (upon receiving a SIGCONT signal).
SIGSTOP cannot be caught, blocked, or ignored. Do not substitute
cancel, end, exit, interrupt, quit, or
terminate. |