Access parameters
You can visit the command-line argument via PROCESS.ARGV, which is an array containing the following:
[Nodebinary, Script, arg0, arg1, ...]
That is, the first argument starts with Process.argv[2], and you can iterate through all the arguments as follows:
Copy Code code as follows:
Process.argv.slice (2). ForEach (function (fileName) {
...
});
If you want to do more complex processing of parameters, you can look at the Node.js module NomNom and optimist. Below, we will use the file system module several times:
Copy Code code as follows:
var fs = require (' FS ');
Read a text file
If your file is not very large, you can read the entire file into memory and place it in a string:
Copy Code code as follows:
var text = Fs.readfilesync (fileName, "UTF8");
Then, you can split the text, and the line of work.
Copy Code code as follows:
Text.split (/\r?\n/). ForEach (function (line) {
// ...
});
For large files, you can use a stream to iterate through all the rows. Mtomis a solution on the stack overflow.
Write a text file
You can write the entire content to a file through a string.
Fs.writefilesync (FileName, str, ' UTF8 ');
Or you can write the string in an incremental way to the stream.
Copy Code code as follows:
var out = Fs.createwritestream (FileName, {encoding: "UTF8"});
Out.write (str);
Out.end (); Currently, the same as Destroy () and Destroysoon ()
Cross-platform considerations
Determines the line terminator.
Resolution 1: Read an existing file into the string, search for "\ r \ n", and determine if the line terminator is "\ n" If it is not found.
Copy Code code as follows:
var EOL = Filecontents.indexof ("\ r \ n") >= 0? "\ r \ n": "\ n";
Solution 2: Test system platform. All Windows platforms return to "Win32", and 64-bit systems are also.
Copy Code code as follows:
var EOL = (Process.platform = = ' Win32 '? ' \ r \ n ': ' \ n ')
Handling paths
You can use the path module when working with file system paths. This ensures that the correct path separator is used (on UNIX, with "/" and "\" on Windows).
Copy Code code as follows:
var path = require (' path ');
Path.join (Mydir, "foo");
Run the script
If your shell's name is myscript.js, then you can run it like this:
Node Myscript.js arg1 arg2 ...
On UNIX, you can add a code to the first line of the script that tells the operating system what program to use to interpret the script:
#!/usr/bin/env node
You must also give the script executable permissions:
chmod u+x Myscript.js
Now the script can run independently:
./myscript.js arg1 Arg2 ...
Other Topics
- output to standard output (stdout): Console.log is the same as in the browser. The console is a global object , not a module, and it does not need to be imported using require () .
- read standard input (stdin): Process.stdin is a readable stream. A process is a global object.
- To run the shell command: through child_process.exec ().
Related articles
- Tip:load source from a file in the Node.js shell
- Execute code each time the Node.js REPL starts
