README
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script is a collection of utilities for doing the kind of tasks that shell scripts are good at: reading files, counting lines, matching strings, and so on. Why shouldn't it be as easy to write system administration programs in Go as it is in a typical shell? script aims to make it just that easy.
Just as the shell allows you to chain operations together into a pipeline, script does the same:
numLines, err := script.File("test.txt").CountLines()
This works because File returns a Pipe object. Most script operations can be methods on a pipe, and will return another pipe, so that you can chain operations indefinitely.
Ultimately, you'll want to read the results from the pipe, and you can do that using the String() method, for example. If the pipe's original data source was something that needs closing, like a file, it will be automatically closed once all the data has been read. script programs will not leak file handles.
If any pipe operation results in an error, the pipe's Error() method will return that error, and all pipe operations will henceforth be no-ops. Thus you can safely chain a whole series of operations without having to check the error status at each stage.
When you eventually read the pipe, for convenience, you will also get the pipe's error status as an extra return value:
p := script.File("doesnt_exist.txt")
out, err := p.String() // err is non-nil
res, err := p.CountLines() // err is non-nil
fmt.Println(p.Error())
// Output: open doesnt_exist.txt: no such file or directory
Documentation
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Overview ¶
Package script aims to make it easy to write shell-type scripts in Go, for general system administration purposes: reading files, counting lines, matching strings, and so on.
Index ¶
- func CountLines(name string) (int, error)
- type Pipe
- func (p *Pipe) Close() error
- func (p *Pipe) CountLines() (int, error)
- func (p Pipe) Echo(s string) *Pipe
- func (p Pipe) Error() error
- func (p Pipe) Match(s string) *Pipe
- func (p Pipe) Reject(s string) *Pipe
- func (p *Pipe) SetError(err error)
- func (p *Pipe) String() (string, error)
- func (p *Pipe) WithCloser(r io.ReadCloser) *Pipe
- func (p *Pipe) WithError(err error) *Pipe
- func (p *Pipe) WithReader(r io.Reader) *Pipe
Constants ¶
This section is empty.
Variables ¶
This section is empty.
Functions ¶
func CountLines ¶
CountLines counts lines in the specified file and returns the integer result, or an error, and closes the pipe after reading. If there is an error reading the pipe, the pipe's error status is also set.
Types ¶
type Pipe ¶
type Pipe struct {
Reader io.ReadCloser
// contains filtered or unexported fields
}
Pipe represents a pipe object with an associated Reader.
func File ¶
File returns a *Pipe associated with the specified file. This is useful for starting pipelines. If there is an error opening the file, the pipe's error status will be set.
func (*Pipe) Close ¶
Close closes the pipe's associated reader. This is always safe to do, because pipes created from a non-closable source will have an `ioutil.NopCloser` to call.
func (*Pipe) CountLines ¶
CountLines counts lines from the pipe's reader, and returns the integer result, or an error. If there is an error reading the pipe, the pipe's error status is also set.
func (Pipe) Match ¶ added in v0.2.0
Match reads from the pipe, and returns a new pipe containing only lines which contain the specified string. If there is an error reading the pipe, the pipe's error status is also set.
func (Pipe) Reject ¶ added in v0.2.0
Reject reads from the pipe, and returns a new pipe containing only lines which do not contain the specified string. If there is an error reading the pipe, the pipe's error status is also set.
func (*Pipe) String ¶
String returns the contents of the Pipe as a string, or an error, and closes the pipe after reading. If there is an error reading, the pipe's error status is also set.
func (*Pipe) WithCloser ¶
func (p *Pipe) WithCloser(r io.ReadCloser) *Pipe
WithCloser takes an io.ReadCloser and associates the pipe with that source.
Source Files