[英]How to show symbolic links like LS -al?
我創建了一個粗略的程序,它使用 C 打印出與 ls -al 類似的提示。雖然它幾乎完美地工作,除了無法動態打印出無法打開的目錄,因為沒有給出參數在當前目錄中運行,所以我想.
就足夠了,但是如果有更好的方法來動態執行此類操作,請告訴我。 我想知道如果下面顯示了任何類似的文件,您如何打印出文件的符號鏈接。
代碼
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <dirent.h>
#include <grp.h>
#include <time.h>
#include <pwd.h>
#include <errno.h>
#include <string.h>
int main(void)
{
DIR *mydir;
DIR *thedir;
struct dirent *myfile;
struct stat myStat;
struct passwd *pwd;
int size = 0;
struct tm lt;
char buf[1024];
char length[100];
long width;
struct group *gf;
int len = 0;
mydir = opendir("./");
thedir = opendir("./");
if(mydir!= NULL){
while((myfile = readdir(thedir)) != NULL){
lstat(myfile->d_name, &myStat);
size += myStat.st_blocks;
width = (long)myStat.st_size;
sprintf(length, "%ld", width);
if(len < strlen(length)){
len = strlen(length);
}
}
printf("total %d\n", size/2);
closedir(thedir);
while((myfile = readdir(mydir)) != NULL)
{
lstat(myfile->d_name, &myStat);
if((lstat(myfile->d_name, &myStat) ) == 0){
pwd = getpwuid(myStat.st_uid);
}
gf = getgrgid(myStat.st_gid);
time_t t = myStat.st_mtime;
localtime_r(&t, <);
char timebuf[80];
char timebuf2[80];
strftime(timebuf, sizeof(timebuf), "%F", <);
strftime(timebuf2, sizeof(timebuf2), "%R", <);
printf( (S_ISDIR(myStat.st_mode)) ? "d" : "-");
printf( (myStat.st_mode & S_IRUSR) ? "r" : "-");
printf( (myStat.st_mode & S_IWUSR) ? "w" : "-");
printf( (myStat.st_mode & S_IXUSR) ? "x" : "-");
printf( (myStat.st_mode & S_IRGRP) ? "r" : "-");
printf( (myStat.st_mode & S_IWGRP) ? "w" : "-");
printf( (myStat.st_mode & S_IXGRP) ? "x" : "-");
printf( (myStat.st_mode & S_IROTH) ? "r" : "-");
printf( (myStat.st_mode & S_IWOTH) ? "w" : "-");
printf( (myStat.st_mode & S_IXOTH) ? "x" : "-");
printf(" ");
printf("%ld ", myStat.st_nlink);
if(pwd != 0){
printf("%s %s %*ld %s %s %s\n", pwd->pw_name, gf->gr_name, len, (long)myStat.st_size, timebuf, timebuf2, myfile->d_name);
}else {
printf("%d %s %*ld %s %s %s\n", myStat.st_uid, gf->gr_name, len, (long)myStat.st_size, timebuf, timebuf2, myfile->d_name);
printf("\n");
}
}
closedir(mydir);
}else{
printf("ls: cannot open directory .: Permission denied");
}
}
電流輸出
total 8
-rw-rw-r-- 1 travis travis 0 2019-04-04 17:11 file2.txt
-rw-rw-r-- 1 travis travis 0 2019-04-04 17:11 file1.txt
drwxrwxr-x 4 travis travis 4096 2019-04-04 17:11 ..
drwxrwxr-x 2 travis travis 4096 2019-04-04 17:11 .
-rwxrwxrwx 1 travis travis 9 2019-04-04 17:11 link1
-rwxrwxrwx 1 travis travis 9 2019-04-04 17:11 link2
期望輸出
total 8
-rw-rw-r-- 1 travis travis 0 2019-04-04 17:11 file2.txt
-rw-rw-r-- 1 travis travis 0 2019-04-04 17:11 file1.txt
drwxrwxr-x 4 travis travis 4096 2019-04-04 17:11 ..
drwxrwxr-x 2 travis travis 4096 2019-04-04 17:11 .
lrwxrwxrwx 1 travis travis 9 2019-04-04 17:11 link1 -> file1.txt
lrwxrwxrwx 1 travis travis 9 2019-04-04 17:11 link2 -> file2.txt
在您的程序中,您查看st_nlink
但它涉及硬鏈接( ln ...
),而不是符號鏈接( ln -s ...
)
查看要寫入的路徑的readlink
概要
#include <unistd.h> ssize_t readlink(const char *pathname, char *buf, size_t bufsiz);
描述
readlink() places the contents of the symbolic link pathname in the buffer buf, which has size bufsiz. readlink() does not append a null byte to buf. It will (silently) truncate the contents (to a length of bufsiz characters), in case the buffer is too small to hold all of the contents.
例如替換
if(pwd != 0){ printf("%s %s %*ld %s %s %s\\n", pwd->pw_name, gf->gr_name, len, (long)myStat.st_size, timebuf, timebuf2, myfile->d_name); }else { printf("%d %s %*ld %s %s %s\\n", myStat.st_uid, gf->gr_name, len, (long)myStat.st_size, timebuf, timebuf2, myfile->d_name); printf("\\n"); }
經過
if(pwd != 0){
printf("%s %s %*ld %s %s %s", pwd->pw_name, gf->gr_name, len, (long)myStat.st_size, timebuf, timebuf2, myfile->d_name);
}else {
printf("%d %s %*ld %s %s %s", myStat.st_uid, gf->gr_name, len, (long)myStat.st_size, timebuf, timebuf2, myfile->d_name);
}
char linkname[PATH_MAX];
ssize_t r = readlink(myfile->d_name, linkname, PATH_MAX);
if (r != -1) {
linkname[r] = '\0';
printf(" -> %s\n", linkname);
}
else
putchar('\n');
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