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Open File (open)

Open a file with a preferred handler

Description

open is a smart tool for reading files:

1. It will read a file from disk or a HTTP(S) endpoints
2. Detect the file type via file extension or HTTP header Content-Type
3. It intelligently writes to stdout

• If stdout is a TTY it will perform any transformations to render to the terminal (eg using inlining images)
• If stdout is a pipe then it will write a byte stream with the relevant data-type

4. If there are no open handlers then it will fallback to the systems default. eg open (on macOS, Linux), open-xdg (X11), etc.

Usage

open filename[.gz]|uri -> <stdout>

Examples

» open https://api.github.com/repos/lmorg/murex/issues -> foreach issue { out "$issue[number]: $issue[title]" }

Detail

File Extensions

Supported file extensions are listed in config under the app and key names of shell, extensions.

Unsupported file extensions are defaulted to generic, *.

Files with a .gz extension are assumed to be gzipped and thus are are automatically expanded.

MIME Types

The Content-Type HTTP header is compared against a list of MIME types, which are stored in config under the app and key names of shell, mime-types.

There is a little bit of additional logic to determine the Murex data-type to use should the MIME type not appear in config, as seen in the following code:

package lang

import (
    "path"
    "regexp"
    "strings"

    "github.com/lmorg/murex/lang/types"
)

var rxMimePrefix = regexp.MustCompile(`^([-0-9a-zA-Z]+)/.*$`)

// MimeToMurex gets the murex data type for a corresponding MIME
func MimeToMurex(mimeType string) string {
    return mimeToMurex(normalizeMime(mimeType))
}
func mimeToMurex(mime string) string {
    // Check suffix
    for suffix := range mimeSuffixes {
        if strings.HasSuffix(mime, suffix) {
            return mimeSuffixes[suffix]
        }
    }

    // Find a direct match
    dt := mimes[mime]
    if dt != "" {
        return dt
    }

    // No matches found. Fall back to prefix
    prefix := rxMimePrefix.FindStringSubmatch(mime)
    if len(prefix) != 2 {
        return types.Generic
    }

    switch prefix[1] {
    case "text", "i-world", "message":
        return types.String

    case "audio", "music", "video", "image", "model":
        return types.Binary

    case "application":
        return types.Generic

    default:
        // Mime type not recognized so lets just make it a generic
        return types.Generic
    }
}

// RequestToMurex attempts to pick a data type for the content of
// a downloaded file using the value of the Content-Type header
// or, if not, the filename. If neither can be used to infer a
// usable data type, types.Generic is returned.
func RequestMetadataToMurex(contentType string, filename string) string {
    contentType = normalizeMime(contentType)

    if !(contentType == "" || contentType == "text/plain") {
        foundType := mimeToMurex(contentType)

        // MimeToMurex will return Generic when it can't find
        // any other matches, but in that case we still want
        // to check the filename ext if possible
        if foundType != types.Generic {
            return foundType
        }
    }

    if filename != "" {
        ext := strings.ToLower(strings.TrimPrefix(path.Ext(filename), "."))
        knownType, foundType := GetFileExts()[ext]

        if foundType {
            return knownType
        }
    }

    return types.Generic
}

// NormalizeMime prepares a mime type for processing by removing charset
// information, trimming leading/trailing spaces, and making it lower case
func normalizeMime(rawMimeType string) string {
    mime := strings.Split(rawMimeType, ";")[0]
    mime = strings.TrimSpace(mime)
    mime = strings.ToLower(mime)

    return mime
}

// MurexToMime returns the default MIME for a given Murex data type.
// The intended use case for this is for GET and POST requests where the body
// is STDIN.
func MurexToMime(dataType string) string {
    return defaultMimes[dataType]
}

HTTP User Agent

open’s user agent is the same as get and post and is configurable via config under they app http

» config -> [http]
{
    "cookies": {
        "Data-Type": "json",
        "Default": {
            "example.com": {
                "name": "value"
            },
            "www.example.com": {
                "name": "value"
            }
        },
        "Description": "Defined cookies to send, ordered by domain.",
        "Dynamic": false,
        "Global": false,
        "Value": {
            "example.com": {
                "name": "value"
            },
            "www.example.com": {
                "name": "value"
            }
        }
    },
    "default-https": {
        "Data-Type": "bool",
        "Default": false,
        "Description": "If true then when no protocol is specified (`http://` nor `https://`) then default to `https://`.",
        "Dynamic": false,
        "Global": false,
        "Value": false
    },
    "headers": {
        "Data-Type": "json",
        "Default": {
            "example.com": {
                "name": "value"
            },
            "www.example.com": {
                "name": "value"
            }
        },
        "Description": "Defined HTTP request headers to send, ordered by domain.",
        "Dynamic": false,
        "Global": false,
        "Value": {
            "example.com": {
                "name": "value"
            },
            "www.example.com": {
                "name": "value"
            }
        }
    },
    "insecure": {
        "Data-Type": "bool",
        "Default": false,
        "Description": "Ignore certificate errors.",
        "Dynamic": false,
        "Global": false,
        "Value": false
    },
    "redirect": {
        "Data-Type": "bool",
        "Default": true,
        "Description": "Automatically follow redirects.",
        "Dynamic": false,
        "Global": false,
        "Value": true
    },
    "timeout": {
        "Data-Type": "int",
        "Default": 10,
        "Description": "Timeout in seconds for `get` and `getfile`.",
        "Dynamic": false,
        "Global": false,
        "Value": 10
    },
    "user-agent": {
        "Data-Type": "str",
        "Default": "murex/1.7.0000 BETA",
        "Description": "User agent string for `get` and `getfile`.",
        "Dynamic": false,
        "Global": false,
        "Value": "murex/1.7.0000 BETA"
    }
}

Open Flags

If the open builtin falls back to using the systems default (like open-xdg) then the only thing that gets passed is the path being opened. If the path is stdin then a temporary file will be created. If you want to pass command line flags to open-xdg (for example), then you need to call that command directly. In the case of macOS and some Linux systems, that might look like:

exec open --flags filename

Synonyms

• open

See Also

• Define Handlers For “open” (openagent): Creates a handler function for open
• Download File (getfile): Makes a standard HTTP request and return the contents as Murex-aware data type for passing along Murex pipelines.
• Execute External Command (exec): Runs an executable
• Execute Shell Function or Builtin (fexec): Execute a command or function, bypassing the usual order of precedence.
• For Each In List (foreach): Iterate through an array
• Get Request (get): Makes a standard HTTP request and returns the result as a JSON object
• Output String (out): Print a string to the stdout with a trailing new line character
• Post Request (post): HTTP POST request with a JSON-parsable return
• Shell Configuration And Settings (config): Query or define Murex runtime settings
• * (generic): generic (primitive)

This document was generated from builtins/core/open/open_doc.yaml.