go-hostlist

Go utility for hostlist expression.

Installation

go get github.com/puttsk/hostlist

Hostlist Expression

Hostlist expression is an expression for specifying a group of hostnames with in various applications, including utilities like pdsh and resource managers like Slurm. This expression allows the concise representation of multiple hostnames. For instance, the expression host-[001-003] is a shorthand for host-001, host-002,and host-003.

In the given example, [001-003] is referred to as a range expression. This expression defines a range of values in the format [i-j,n-m,..], where i,j,n,and m are integer with the contraint i < j, and n < m. Although a range expression can accommodate string values, it does not support character ranges like [a-c].

Example of valid range expression: [1-10,11,100-101], [a,b,c], [a,22-25]

Usage

Hostlist package contains two main functions Expand and Compress.

Expand recieves a hostlist expression and returns a list of hostname contained in the expression.

Example:

hosts, err := hostlist.Expand("host-[001-003]")
if err != nil {
    fmt.Print("Error: " + err.Error())
}

// Print host-001 host-002 host-003
fmt.Printf("%s\n", strings.Join(hosts, " ")) 

Compress recieves a list of hostnames and return a hostlist expression representing the list.

Example:

hosts := []string{"host-001","host-oo2","host-003"}
expr, _ := hostlist.Compress(hosts)

// Print host-[001-003]
fmt.Println(expr)

Command Line Interface

> hostlist -h
Usage of ./hostlist:
  -c    See. -compress
  -compress
        Compress list of hostnames to hostlist expression
  -e    See. -expand
  -expand
        Expand hostlist expression

Expand hostlist expression

> hostlist -e "host[001-004]"
host001 host002 host003 host004

> hostlist -e "192.168.[0-1].[211-213]"
192.168.0.211 192.168.0.212 192.168.0.213 192.168.1.211 192.168.1.212 192.168.1.213

Compress hostlist expression

> hostlist -c host001 host002 host003 host004 
host[001-004]

> hostlist -c 192.168.0.211 192.168.0.212 192.168.0.213 192.168.1.211 192.168.1.212 192.168.1.213
192.168.[0-1].[211-213]

Contributing

TBD

Authors

• Putt Sakdhnagool - Initial work

See also the list of contributors who participated in this project.

Issues / Feature request

You can submit bug / issues / feature request using Tracker.

Known Issues

• Current implementation of Expand does not accept a nested range expression, e.g., [01-02,a[03-04]]
• The result of Expand an hostlist expression following by Compress might not results in the same input hostlist expression.
• In some scenario, Compress generates nested range expression, which is not supported by Expand function

License

MIT License.