hostlist

README

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.

Documentation

Overview

Package hostlist provides utility function for working with hostlist expression Hostlist expression provides a way to define a range of hostnames without an explicit list.

Index

• func Compress(hosts []string) (string, error)
• func Expand(expression string) ([]string, error)

Functions

func Compress

func Compress(hosts []string) (string, error)

Compress return hostlist expression from a list of host

func Expand

func Expand(expression string) ([]string, error)

Expand expands hostnames from hostlist expression and return an array of hostnames.

For example:

`host-[001-003]` will be converted to `["host-001", "host-002", "host-003"]`