【Shell 命令集合 文档编辑】Linux 格式化文本文件fmt命令使用教程

fmt [OPTION]... [FILE]...

$ cat file.txt
This is a sample text file used for demonstration purposes.
$ fmt file.txt
This is a sample text file used for demonstration purposes.
$ fmt -w 20 file.txt
This is a sample
text file used for
demonstration
purposes.
$ fmt -c file.txt
This is a sample text file used
for demonstration purposes.
$ fmt -s file.txt
This is a sample text file used for demonstration purposes.
$ fmt -p file.txt
 This is a sample text file used for demonstration purposes.

fmt [选项] [文件...]

$ cat file1.txt
This is a sample text file used for demonstration purposes.
$ fmt file1.txt
This is a sample text file used for demonstration purposes.

$ cat file2.txt
This is a long line of text that needs to be formatted into multiple lines.
$ fmt -w 20 file2.txt
This is a long line
of text that needs to
be formatted into
multiple lines.

$ cat file3.txt
This is a paragraph. It consists of multiple sentences. Each sentence needs to be on a separate line.
$ fmt -c file3.txt
This is a paragraph. It consists of multiple sentences. Each sentence needs to be on a separate line.

$ cat file4.txt
This is a tagged paragraph.
> It starts with a tag symbol.
> Each line starts with a tag symbol.
$ fmt -t file4.txt
This is a tagged paragraph. It starts with a tag symbol. Each line starts with a tag symbol.

$ cat file5.txt
This is a sample text file used for demonstration purposes.
$ fmt -s file5.txt
This is a sample text file used for demonstration purposes.

$ cat file6.txt
This is a sample text file used for demonstration purposes.
$ fmt -p file6.txt
 This is a sample text file used for demonstration purposes.

$ cat file7.txt
This is a sample text file used for demonstration purposes.
$ fmt -w 30 -c file7.txt
This is a sample text file
used for demonstration
purposes.

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define MAX_LINE_WIDTH 80
// 函数原型
void fmt(FILE *inputFile, FILE *outputFile, int lineWidth);
int main(int argc, char *argv[]) {
    // 检查命令行参数
    if (argc != 2) {
        printf("Usage: ./fmt <input_file>\n");
        return 1;
    }
    // 打开输入文件
    FILE *inputFile = fopen(argv[1], "r");
    if (inputFile == NULL) {
        printf("Error opening input file.\n");
        return 1;
    }
    // 打开输出文件
    FILE *outputFile = fopen("output.txt", "w");
    if (outputFile == NULL) {
        printf("Error opening output file.\n");
        return 1;
    }
    // 调用 fmt 函数进行格式化处理
    fmt(inputFile, outputFile, MAX_LINE_WIDTH);
    // 关闭文件
    fclose(inputFile);
    fclose(outputFile);
    printf("Formatting complete.\n");
    return 0;
}
// 格式化函数
void fmt(FILE *inputFile, FILE *outputFile, int lineWidth) {
    char line[MAX_LINE_WIDTH];
    int currentWidth = 0;
    while (fgets(line, sizeof(line), inputFile)) {
        // 去除行尾的换行符
        line[strcspn(line, "\n")] = '\0';
        // 如果行为空，直接写入输出文件
        if (line[0] == '\0') {
            fputs(line, outputFile);
            fputs("\n", outputFile);
            currentWidth = 0;
            continue;
        }
        // 如果当前行已经超过指定宽度，写入输出文件并重置当前宽度
        if (currentWidth + strlen(line) > lineWidth) {
            fputs("\n", outputFile);
            currentWidth = 0;
        }
        // 在当前行后添加空格或者换行符
        if (currentWidth > 0) {
            fputs(" ", outputFile);
            currentWidth++;
        }
        // 写入当前行内容
        fputs(line, outputFile);
        currentWidth += strlen(line);
    }
}