JavaScript uses Node. js to write Shell scripts.

Access Parameters
You can use process. argv to access the command line parameters. It is an array containing the following content:

[NodeBinary, script, arg0, arg1,...]

That is to say, the first parameter starts from process. argv [2]. You can traverse all parameters as follows:Copy codeThe Code is as follows: process. argv. slice (2). forEach (function (fileName ){
...
});

If you want to perform more complex processing on parameters, you can take a look at the Node. js module nomnom and optimist. Below, we will use the File System Module Multiple times:Copy codeThe Code is as follows: var fs = require ('fs ');

Read a text file
If your file is not large, you can read the entire file into the memory and put it in a string:Copy codeThe Code is as follows: var text = fs. readFileSync (fileName, "utf8 ");

Then, you can split the text and process it in one row.Copy codeThe Code is as follows: text. split (/\ r? \ N/). forEach (function (line ){
//...
});

For large files, you can use a stream to traverse all rows. mtomis provides a solution on Stack Overflow.

Write a text file
You can write the complete content into a file using a string.

Fs. writeFileSync (fileName, str, 'utf8 ');
Alternatively, you can incrementally write strings to the stream.Copy codeThe Code is as follows: var out = fs. createWriteStream (fileName, {encoding: "utf8 "});
Out. write (str );
Out. end (); // It is the same as destroy () and destroySoon ().

Cross-platform considerations

Determines the line terminator.
Solution 1: read an existing file to the string and search for "\ r \ n". If not found, the line terminator is "\ n ".Copy codeThe Code is as follows: var EOL = fileContents. indexOf ("\ r \ n")> = 0? "\ R \ n": "\ n ";

Solution 2: Detection System Platform. "win32" is returned for all Windows platforms, and for 64-bit systems.Copy codeThe Code is as follows: var EOL = (process. platform = 'win32 '? '\ R \ N':' \ n ')

Process paths

You can use the path module when processing the file system PATH. This ensures that the correct path separator is used ("/" on Unix and "\" on Windows "\").Copy codeThe Code is as follows: var path = require ('path ');
Path. join (mydir, "foo ");

Run scripts
If your shell script is named myscript. js, you can run it like this:

Node myscript. js arg1 arg2...

On Unix, you can add a code in the first line of the script to tell the operating system what program to use to explain the script:

#! /Usr/bin/env node

You must also grant the executable permission to the script:

Chmod u + x myscript. js
Now the script can run independently:

./Myscript. js arg1 arg2...

Other topics

• Output to standard output (stdout ): Console. logSame as in a browser.Console is a global objectIt is not a module and does not need to be used.Require () Import.
• Read standard input (stdin ): Process. stdinIs a readable stream.ProcessIs a global object.
• Run the shell command:Child_process.exec ().

Related Articles

1. Tip: load source from a file in the Node. js shell
2. Execute code each time the Node. js REPL starts