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How to write files in Linux:
1. Use fwrite function
Function function
Use to read and write a data block.
General calling form
fwrite(buffer,size,count,fp);
Explanation
(1) buffer: It is a pointer. For fread, it is the storage address of the read data. For fwrite, it is the address of the data to be output.
(2) size: the number of bytes to be read and written;
(3) count: how many size bytes of data items to be read and written;
( 4) fp: file pointer
Example:
A program that writes the current time into text.
int markfile(void ) { FILE *sp ; // char buff[512] ; char count = 0; char *currentime = NULL; char *wday[] = {"Sun","Mon","Tue","Wed","Thu","Fri","Sat"}; time_t timep; struct tm *p; time(&timep); p = localtime(&timep); currentime = ctime(&timep); // memset(buff,0,512); // sprintf(buff,"%s",currentime); printf("%d/%d/%d",(1900+p->tm_year),(1+p->tm_mon),p->tm_mday); printf(" %s %d:%d:%d\n",wday[p->tm_wday],p->tm_hour,p->tm_min,p->tm_sec); if((sp = fopen("/root/kay/mark.txt","a+")) == NULL) return 0; fwrite(currentime,size(currentime)-1,1,sp); fclose(sp); return 1; }
2. Use the echo command
The command format is as follows:
[root@localhost ~]# echo [选项] [输出内容]
Options:
-e: Supports character conversion controlled by backslash (see Table 1 for details)
-n: Cancel the newline symbol at the end of the line after output (no line break after the content is output)
Example:
echo 'i love u' >a.txt *在a.txt这个文件中输入i love u,如果没有这个文件则创建。如果有这个文件,那么 新内容代替原来的内容。
Recommended learning: linux tutorial
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