73 lines
1.7 KiB
JavaScript
73 lines
1.7 KiB
JavaScript
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var common = require('./common');
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var fs = require('fs');
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common.register('tail', _tail, {
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canReceivePipe: true,
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cmdOptions: {
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'n': 'numLines',
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},
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});
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//@
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//@ ### tail([{'-n': \<num\>},] file [, file ...])
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//@ ### tail([{'-n': \<num\>},] file_array)
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//@ Available options:
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//@
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//@ + `-n <num>`: Show the last `<num>` lines of the files
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//@
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//@ Examples:
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//@
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//@ ```javascript
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//@ var str = tail({'-n': 1}, 'file*.txt');
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//@ var str = tail('file1', 'file2');
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//@ var str = tail(['file1', 'file2']); // same as above
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//@ ```
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//@
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//@ Read the end of a file.
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function _tail(options, files) {
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var tail = [];
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var pipe = common.readFromPipe();
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if (!files && !pipe) common.error('no paths given');
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var idx = 1;
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if (options.numLines === true) {
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idx = 2;
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options.numLines = Number(arguments[1]);
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} else if (options.numLines === false) {
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options.numLines = 10;
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}
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options.numLines = -1 * Math.abs(options.numLines);
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files = [].slice.call(arguments, idx);
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if (pipe) {
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files.unshift('-');
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}
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var shouldAppendNewline = false;
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files.forEach(function (file) {
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if (!fs.existsSync(file) && file !== '-') {
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common.error('no such file or directory: ' + file, { continue: true });
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return;
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}
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var contents = file === '-' ? pipe : fs.readFileSync(file, 'utf8');
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var lines = contents.split('\n');
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if (lines[lines.length - 1] === '') {
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lines.pop();
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shouldAppendNewline = true;
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} else {
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shouldAppendNewline = false;
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}
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tail = tail.concat(lines.slice(options.numLines));
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});
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if (shouldAppendNewline) {
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tail.push(''); // to add a trailing newline once we join
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}
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return tail.join('\n');
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}
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module.exports = _tail;
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