Command-Line Flags with Go-Lang
Nov 3 · 1 min read
Command-line flags are a common way to specify options for command-line exercutable. Go provides a flag package supporting basic command-line flag parsing. This article shows how to pass CLI flag options to a running executable.
Flags are defined using flag.String(), Bool(), Int(), etc. Depending on the intended datatype.
First argument — Flag name
Second argument — Default value
Third argument — help message for flag nameinstances := flag.Int(“instances”, 5, “number of deployed instance”)
After all flags are defined, call
flag.Parse()to parse the command line into the defined flags.
Command line flag syntax
The following forms are permitted:
-flag
-flag=x
-flag x // non-boolean flags only
- h -> displays flag documentation
$ go build flags.go
./flag -h
-instances int
number of deployed instances (default 5)$ ./flags -instances 7
