- /*BASIC UNIX AND NETWORKING COMMANDS*/
BASIC UNIX COMMANDS
passwd:
This command allows you to change your login password. You are propted to enter your current password, and then prompted (twice) to enter your new password.
OUTPUT:
[2mcaa17mca24~]$ passwd
changing password for user 2mcaa2
changing password for 2mcaa2
(current) UNIX password:
New UNIX password:
Retype new UNIX password.
passwd: all authentication token updated successfully.
cd:
This command, as in DOS changes directories. You can use to represent the directory above the current directory.
syntax: cd directory name
OUTPUT:
[2mcaa17@mca24~]$ cd khs
[2mcaa17@mca24~ khs]$
pwd:
This command tells you which directory you are currently working in, your home directory from anywhere, type cd~, however typing cd without the ~ also works on Linux system.
OUTPUT:
[2mcaa2@mca24~]$ pwd
/home/2mcaa2/khs
ls:
This gives you listing of all files in a directory. You cannot tell which files are and which directories are.
OUTPUT:
arms.sh fibb.sh fibo.sh reverse.sh
sqcu.sh sum.sh swapping.sh
ls-f:
This shows which files are normal files (they have no special symbols at the end), which are directories (they end in a/character), which are links (they end in a @ symbol) and which are executables (they end in a *character). There special symbol are NOT part of the file name.
OUTPUT:
.creat.c.swo .zshre . .. .bash_logout
.bashrc .swp .add.sh.swp .swm.sh swapping.sh
.creat.sh.swp .fork.c.swp .fibb.sh.swp swapp.sh .viminfo
arms.sh .bash_profile fibo.sh .bash_history .kde
.sqcu.sh .creat.c.swp
ls-l:
"Long" format. Gives more details about the files and directories in the current directory.
OUTPUT:
[2mcaa2@mca24~]$ ls-l
total 32
-rw-r--r-- 1 2mcaa2 2mcaa2 232 Jul 1 19:44 arms.sh
-rw-r--r-- 1 2mcaa2 2mcaa2 197 Jul 2 19:17 fibb.sh
-rw-r--r-- 1 2mcaa2 2mcaa2 233 Jul 2 19:16 fibo.sh
-rw-r--r-- 1 2mcaa2 2mcaa2 124 Jul 4 16:44 revere.sh
-rw-r--r-- 1 2mcaa2 2mcaa2 160 Jul 6 20:29 sqcu.sh
-rw-r--r-- 1 2mcaa2 2mcaa2 157 Jul 6 19:42 sum.sh
-rw-r--r-- 1 2mcaa2 2mcaa2 175 Jul 6 20:22 swapp.sh
ls-a:
List "hidden" files in current directory (Those starting with a. character).
OUTPUT:
. arms.sh .bash_profile .create.c.swp .fibb.sh.swp .kde
.sww.sh swp .. .bash_history .fibo.sh reverse.sh .\sqcu.sh .fork.c.swp .zshrc .bash.logout
ls-la:
Options may usually be combined. This particular combination would list both hidden and unhidden files in the long format.
OUTPUT:
total 176
drwx----- 3 2mcaa2 2mcaa2 4096 Jul 6 20:29 .
drwxr-xr-x 386 root root 12288 Jul 30 15:00 ..
-rw------ 1 2mcaa2 2mcaa2 12288 Dec 12 2008 .
-rw-r--r-- 1 2mcaa2 2mcaa2 232 Jul 1 19:44 arms.sh
-rw-r--r-- 1 2mcaa2 2mcaa2 197 Jul 2 19:17 fibb.sh
mv:
The "move" command is how you rename files.
Syntax: mv oldfilename newfilename
OUTPUT:
[2mcaa2@mca24~]$ mv swapp.sh swap.sh
[2mcaa2@mca24~]$ ls
arms.sh fibb.sh fibo.sh reverse.sh swap.sh
cp:
Allowos you to copy one or more files.
syntax: cp oldfilename.sh newfilename.sh
OUTPUT:
[2mcaa2@mca24~]$ cp fibb.sh fibonaci.sh
rm:
Deletes a file. BE CAREFULL!! There is no "undeleted" command.
syntax: rm filename.sh
OUTPUT:
[2mcaa2@mca24~]$ rm sum.sh
cat:
Sends the contents of a file to stdout (usually the display screen). The name comes from "concatenate".
syntax: cat
OUTPUT:
[2mcaa2@mca24~]$ cat
Welcome to all
Welcome to all
more:
Like cat but display a files one page a time.
syntax: more filename.sh
OUTPUT:
[2mcaa2@mca24~]$ more arithmetic.sh
echo "Read two values";
read a b;
c='expr $a + $b';
d='expr $a - $b';
e='expr $a /* $b';
f='expr $a % $b';
echo "c = $c";
echo "d = $d";
echo "e = $e";
echo "f = $f";
wc:
Counts the number of lines, words and characters in a file.
Syntax: wc filename.sh
OUTPUT:
[2mcaa2@mca24~]$ wc arithmetic.sh
10 35 163 arithmetic.sh
tail-n:
Display the last n lines of a file.
Syntax: tail-n lines filename.sh
OUTPUT:
[2mcaa2@mca24~]$ tail -2 arithmetic.sh
echo "e = $e";
echo "f = $f";
head-n:
Display the first n lines of a file.
Syntax: head -n filename.sh
OUTPUT:
[2mcaa2@mca24~]$ head -3 arithmetic.sh
echo "Read two values";
read a b;
c = 'expr $a + $b';
mkdir:
Creates a new directory, located below the presents directory. (Use pwd first tp check where you are)
Syntax: mkdir directoryname
OUTPUT:
[2mcaa2@mca24~]$ mkdir khs
rmdir:
Deletes a directory.
Syntax: rmdir directoryname
OUTPUT:
[2mcaa2@mca24~]$ rmdir khs
man:
The most important UNIX command. It displays the manual pages fir a chosen UNIX command. Press [Enter] to advance one line, [Spacebar] to advance one page, and [Q] key to quit and return to the UNIX prompt.
Syntax: man mkdir
OUTPUT:
NAME mkdir -make directories
SYNOPSIS mkdir [OPTION] DIRECTORY....
DESCRIPTION
Create the DIRECTORY(ies), if they do not already exits.
Mandatory arguments to long options are mandatory for short options too.
-z, --context = CONTEXT (SE Linux) set security context to CONTEXT.
-m, --mode = NODE
set permission mode (as in chmod), not rwxrwxrwx -unmask.
AUTHOR
Written by David Mackenzie.
REPORTING BUGS
Report bugs to <bug-coreutils@gnu.org>.
man-k:
Displays all UNIX commands related to a given keyword.
Syntax: man command -k
OUTPUT:
[2mcaa2@mca24~]$ man mkdir -k
mkdir (1) - make directories
mkdir (2p) - make directories
mkdir (2) - create a directory
mkdir (3p) - make a directory
mkdirat (2) - create a directory relative to a directory file descriptor
mkdir hier (1x) - makes a directory hierarchy
date:
Shows the current time and date.
syntax: date
OUTPUT:
[2mcaa2@mca24~]$ date
Wed Jul 8 20:49:48 IST 2009
logout:
Terminate the current login session, land returns you to your telnet client, if that is how you established the session originally.
syntax: logout
OUTPUT:
[2mcaa2@mca24~]$ logout
There are stopped jobs
[2mcaa2@mca24~]$
2./* CREATE OPEN CLOSE SYSTEM CALL */
#include<stdio.h>
#include<stdlib.h>
#include<fcntl.h>
#include<unistd.h>
#include<sys/types.h>
int main(int argc, char *argv[])
{
int fd1;
char buf[4096];
fd1=creat(argv[1],O_WRONLY);
if(fd1<0)
{
printf("\n error creating file %s \n",argv[1]);
exit(0);
}
close(fd1);
printf("/n fib %s is created sucessfully", argv[1]);
}
OUTPUT:
[2mcaa17@mca24 ~]$ vim rlab2.c
[2mcaa17@mca24 ~]$ gcc rlab2.c
[2mcaa17@mca24 ~]$ ./a.out rexample.c
/n fib rexample.c is created successfully
[2mcaa17@mca24 ~]$./a.out rexample.c
error creating file rexample.c
[2mcaa17@mca24 ~]$ ./a.out
error creating file (null)
3. /* EXEC SYSTEM CALL */
#include<unistd.h>
#include<stdio.h>
#include<sys/types.h>
#include<sys/stat.h>
#include<stdlib.h>
#include<fcntl.h>
int system(const char * cmd)
{
pid_t pid;
int status;
if(cmd==NULL)
status = 1;
else if((pid=fork())<0)
status = -1;
else if(pid==0)
{
printf("\n\n Now executing command %s \n \n",cmd );
sleep(2);
execl("/bin/sh","sh","c",cmd,(char *)0);
_exit(127);
}
return(status);
}
int main()
{
int st;
st=system("date");
st=system("uname -a");
}
OUTPUT:
/* EXEC SYSTEM CALL */
[2mcaa17@mca24 ~]$ vim rlab8.c
[2mcaa17@mca24 ~]$ gcc rlab8.c
[2mcaa17@mca24 ~]$ ./a.out
Now executing command date
Now executing command uname -a
4. /*LSEEK SYSTEM CALL */
#include<stdio.h>
#include<unistd.h>
#include<sys/types.h>
#include<sys/stat.h>
#include<stdlib.h>
#include<fcntl.h>
int main(int argc,char *argv[])
{
int lv,ret,fd,n;
char buff[4096];
fd=open(argv[1],O_RDONLY);
lv=lseek(fd,0,SEEK_END);
lseek(fd,0,SEEK_SET);
printf("LV=%d,LV/2=%d",lv,lv/2);
while((ret=read(fd,buff,4096))!=-1)
{
write(STDOUT_FILENO,buff,lv/2);
printf("\n\n");
exit(0);
}
}
/*LSEEK SYSTEM CALL */
OUTPUT:
[2mcaa17@mca24 ~]$ vim rlab6.c
[2mcaa17@mca24 ~]$ gcc rlab6.c
[2mcaa17@mca24 ~]$ ./a.out rlab1.c
#include <sys/types.h>
#include <sys/stat.h>
#include<stdio.h>
#include<stdlib.h>
main(int argc,char *argv[])
{
int i;
struct stat statbuff;
char *ptr;
for(i=1; i<argc; i++)
{
printf ("%s",argv[i]);
if(stat(argv[i],&statbuff)<0)
printf("fstat error");
switch(statbuff.st_mode & S_IFMT)
{
case S_IFDIR: ptr="directory";
break;
case S_IFCHR: ptr="charac
LV=702,LV/2=351
5. /*FILE TYPES */
#include <sys/types.h>
#include <sys/stat.h>
#include<stdio.h>
#include<stdlib.h>
main(int argc,char *argv[])
{
int i;
struct stat statbuff;
char *ptr;
for(i=1; i<argc; i++)
{
printf ("%s",argv[i]);
if(stat(argv[i],&statbuff)<0)
printf("fstat error");
switch(statbuff.st_mode & S_IFMT)
{
case S_IFDIR: ptr="DIRECTORY";
break;
case S_IFCHR: ptr="CHARACTER ";
break;
case S_IFBLK: ptr="BLOCK SPECIAL";
break;
case S_IFREG:
ptr="REGULAR";
break;
#ifdef S_IFLINK
case S_IFLINK:
ptr="SYMBOLIC LINK";
break;
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