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6.
, :
[_] [-a |-b] [-o ],
-a -b .
-a - , ;
-b - .
, -o.
.
, , , , . open().
#include <fcntl.h.>
#include<sys/types.h
#include<sys/stat.h>
int open(char *filename, int flags, [mode_t mode]);
char *filename , ( ).
int flags .
[mode_t mode] . . POSIX , mode_t mode, :
S_IRWXU , ;
S_IRUSR ;
S_IWUSR ;
S_IXUSR ;
S_IRWXG , ;
.
sys/stat.h. .
open() , .
, (||). open(), fcntl.h.
open(), fcntl.h:
O_RDONLY ;
O_WRONLY ;
O_RDWR ;
O_CREAT , ;
O_TRUNC , . ;
O_APPEND . , . , lseek();
O_EXCL , ( O_CREATE)
O_NONBLOCK , . , . .
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, . . , , O_RDONLY O_WRONLY, .
open() , -1, , errno .
.
(environment) =. . , :
$ env
env. Linux- , :
USER ;
HOME ;
PATH , ;
SHELL ;
PWD .
:
$ echo $VARIABLE
VARIABLE . , $VARIABLE .
:
1. environ, =. unistd.h.
2. getenv(), . stdlib.h
getenv() .
:
#include <stdlib.h>
char *getenv(const char *name);
name , , HOME PATH. , getenv() . , NULL.
environ , argv . . POSIX, environ .
extern char **environ;
argv, environ NULL. , , argc.
. UNIX , , .
, main():
int main(int argc, char *argv[], char *envp[])
envp , environ.
, :
int setenv(const char *name, const char *value, int overwrite); //
int putenv(char *string); // , .
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void unsetenv(const char *name); // .
int clearenv(void); // .
.
getopt() . getopt() , optstring.
, extern, .
#include<unistd.h>
int getopt(int argc, char *const argv[], const char *optstring);
extern char *optarg;
extern int optind, opterr, optopt;
- argc ( ) argv ( ) , main();
- optstring ;
- optind (c 1) argv[].
(argc), (argv) (optstring), getopt() . . , , -1, .
, getopt(), :
- optarg , ( ).
- optind argv, getopt().
- optopt , ( ) .
optstring .
getopt() , -1; - , .
getopt() , , -1. , . getopt() optstring ( ). optstring , . optarg optind. , optstring , . , opstring, , opstring : , ? .
optopt . , ( getopt , . opterr ). opterr . getopt() , , optopt "?". , opterr.
opterr ( ), getopt() . opterr , getopt() "?" ":"
, optopt .
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, optind , argv . , , optind.
, getopt() argv[optind] (, ), -1 , .
.
close() : , . . close() unistd.h :
#include <unistd.h>
int close (int fd);
0, -1. , . errno.
.
write() read() POSIX:
#include<unistd.h>
#include<sys/types.h>
ssize_t write(int fd, const void *buf, size_t size);
write(), , fd, size buf. , , , .
, . -1 errno. write() 0, , .
. .
, , ( ) , . , . . \0, , , . , ,
, .
sprintf().
sprintf() , printf, .
:
#include <stdio.h>
int sprintf(char *string, const char *format, apr1, apr2, )
sprintf() apr1, apr2 .., format, (stdout), string ( ). , string .
strlen().
char, . , . \0. . 10 , 11 .
:
#include <string.h>
int strlen(char *string);
strlen(). strlen() , , \0. strlen() <string.h>.
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strlen() . sizeof , "" -, . , , .
getenv() , , name. = .
getenv () NULL, . Sysinfo - .
Uname - .
, .
, b . ,
: , .
#include<unistd.h>
#include<stdio.h>
#include<stdlib.h>
#include<fcntl.h>
#include<sys/types.h>
#include<sys/stat.h>
int main(int argc, char*argv[])
{
int t;
int c;
int aflag=0;
int bflag=0;
int errflag=0;
int flag='?';
char*ofile=NULL;
opterr=0;
if (argc!=4)
{ printf(":%s:[-a|-b][-o ]\n",argv[0]);
return 1;
}
while((c=getopt(argc,argv,":abo:"))!=-1)
{
switch(c)
{
case 'a':aflag++;
flag=c;
if(bflag)
{
printf(" a b \n");
errflag++;
}
break;
case 'b':bflag++;
flag=c;
if(aflag)
{
printf(" a b \n");
errflag++;
}
break;
case 'o':ofile=optarg;
break;
case':':printf(" -%c\n",optopt);
errflag++;
break;
}
}
if(errflag)
{(void)printf(":%s:[-a|-b][-o ]\n",argv[0]);
return(1);
}
printf(" :%c\n",flag);
printf(" o: %s\n",ofile);
printf(" : ");
char pr;
printf(" ?");
printf(" [m] / [g] \n");
scanf("%c", &pr);
if (pr=='m')
{
for (;optind<argc;optind++)
{
printf("%s",argv[optind]);
}
printf("\n");
{
int outfile;
char buf[100];
switch(flag)
{
case 'a':
printf("\n");
system("echo 'Imya directorii v kotoroy okazivaetsya koristuva4 posle zapuska v sistemu: ';cd; pwd");
sprintf (buf,"pwd > %s",argv[optind-1]);
system(buf);
break;
case 'b':
system("echo 'Imya terminala: '; tty");
sprintf(buf,"tty > %s",argv[optind-1]);
system(buf);
break;
}
}
}
else
{
for (;optind<argc;optind++)
{
printf("%s",argv[optind]);
}
printf("\n");
char * var;
char buf[100];
switch(flag)
{
case 'a':
var=getenv ("HOME");
printf(" :%s\n",var);
sprintf(buf," :%s\n",var);
break;
case 'b':
var=getenv ("TERM");
printf(" :%s\n",var);
sprintf(buf," :%s\n",var);
break;
}
char t;
int outfile;
outfile=open(argv[optind-1],O_RDWR,0644);
if (outfile!=-1)
{
printf("\n ! \n ( [c]? \n ? [r]");
scanf("%c",&t);
scanf("%c",&t);
if (t=='y')
lseek(outfile,0,SEEK_END);
}
else if (outfile==-1)
outfile=open(argv[optind-1],O_RDWR|O_CREAT,0644);
write(outfile,buf,100);
{
printf("\n");
close(outfile);
}
}
return (0);
}
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, Linux.
uname, sysinfo getenv system.
system string Linux.
