Transcript UNIX

Lecture 3: Unix installation&testing
Guntis Barzdins
Girts Folkmanis
Juris Krumins
Mājas darbs #1:
 Katram instalēt atšķirīgu* Unix paveidu
 Pētījumā (aptuveni 5-10 lpp) aprakstīt gūto pieredzi:
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Ar ko šī Unix versija atšķiras no citām, kāpēc to izvēlējāties
Unix instalācijas process
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Galveno soļu screenshoti
Svarīgākās konfigurācijas opcijas, jūsu izvēle
Izveidot lietotāju “lapsa”, pārbaudīt ka var pieslēgties
Aplikācijas “toyshell” kompilācija, uzlabošana
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Nokompilēt un pārbaudīt “toyshell” darbību
Papildināt “toyshell” funkcionalitāti (help, cd, ctrl/D, setenv,...)**
Panākt lai lietotājs “lapsa” pieslēdzoties nonāk jūsu “toyshell” un
var tajā veikt sakarīgas darbības
* - vairāku vienādu Unix paveidu gadījumā, vērtējums būs stingrāks
** - vairāk signāli, systemcall vērtējumu uzlabos
#include <stdlib.h>
#include <stdio.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <unistd.h>
#include <signal.h>
#define MAXLINE 200
#define MAXARG 20
extern char **environ;
void env(void){
int i;
for(i=0;environ[i]!=NULL;i++){
printf("%s\n",environ[i]);
}
}
void exitsh(int status){
_exit(status);
}
void execute(char *arg[]){
pid_t pid;
int status;
pid=fork();
if(pid>0){
wait(&status);
} else if (pid==0) {
execvp(arg[0],arg);
printf("Komanda nav atrasta\n");
exitsh(0);
} else {
printf("Kluda fork() sistemas
izsaukuma\n");
}
}
toyshell.c
int main (void){
char cmd[MAXLINE];
char *cmdp;
char *av[MAXARG];
int i;
while(1){
printf("$toyshell$> ");
fgets(cmd,sizeof(cmd),stdin);
if(strcmp(cmd,"env\n")==0){
env();
} else if(strcmp(cmd,"exit\n")==0){
exitsh(0);
} else {
cmdp=cmd;
for(i=0;i<MAXARG;i++){
av[i]=strtok(cmdp," \t\n");
cmdp=NULL;
}
execute(av);
}
}
return(0);
}
“toyshell” palaišana
# /usr/bin/gcc toyshell.c
# cc toyshell.c
# ./a.out
$toyshell$> env
USER=root
HOME=/root
TERM=vt100
PATH=/root/bin:/usr/local/bin:/bin:/usr/bin
SHELL=/bin/sh
$toyshell$> ps
PID TTY TIME CMD
126 co 0:00 -sh
95 c1 0:00 getty
435 p1 0:00 ./a.out
436 p1 0:00 ps
$toyshell$> exit
#
passwd, shadow, group files
unix etc # ls -l passwd shadow group
-rw-r--r-- 1 root root 705 Sep 23 15:36 group
-rw-r--r-- 1 root root 1895 Sep 24 18:20 passwd
-rw------- 1 root root 634 Sep 24 18:22 shadow
unix etc #
unix root # more /etc/passwd
root:x:0:0:root:/root:/bin/bash
bin:x:1:1:bin:/bin:/bin/false
daemon:x:2:2:daemon:/sbin:/bin/false
adm:x:3:4:adm:/var/adm:/bin/false
lp:x:4:7:lp:/var/spool/lpd:/bin/false
sync:x:5:0:sync:/sbin:/bin/sync
shutdown:x:6:0:shutdown:/sbin:/sbin/shutdown
halt:x:7:0:halt:/sbin:/sbin/halt
...
guest:x:405:100:guest:/dev/null:/dev/null
nobody:x:65534:65534:nobody:/:/bin/false
girtsf:x:1000:100::/home/girtsf:/bin/bash
dima:x:1001:100::/home/dima:/bin/bash
guntis:x:1002:100::/home/guntis:/bin/bash
students:x:1003:100::/home/students:/bin/bash
unix root #
unix root # more /etc/shadow
root:$1$VlYbWsrd$GUs2cptio.rKlGHgAMBzr.:12684:0:::::
halt:*:9797:0:::::
...
guest:*:9797:0:::::
nobody:*:9797:0:::::
girtsf:$1$u6UEWKT2$w5K28n2iAB2wNWtyPLycP1:12684:0:99999:7:::
dima:$1$BQCdIBdV$xzzlj4s8XT6L9cLAmcoV50:12684:0:99999:7:::
guntis:$1$fiJF/0BT$Py9JiQQL6icajjQVyMZ7//:12684:0:99999:7:::
students:$1$wueon8yh$nLpUpNOKr8yTYaEnEK6OJ1:12685:0:99999:7:::
unix root #
unix root # more /etc/group
root::0:root
bin::1:root,bin,daemon
daemon::2:root,bin,daemon
sys::3:root,bin,adm
adm::4:root,adm,daemon
tty::5:girtsf
disk::6:root,adm
lp::7:lp
mem::8:
kmem::9:
wheel::10:root,girtsf
floppy::11:root
mail::12:mail
...
users::100:games,girtsf
nofiles:x:200:
qmail:x:201:
postfix:x:207:
postdrop:x:208:
smmsp:x:209:smmsp
slocate::245:
portage::250:portage
utmp:x:406:
nogroup::65533:
nobody::65534:
unix root #
Security in UNIX
cp a.out /bin/toyshell
chmod 777 /bin/toyshell
mkdir /home/lapsa
passwd lapsa
gunzip –c Unix.tar.gz | tar –xvf -
Hard Drive Construction
Master Boot Record (MBR):
Track 0, Sector 1
• Number of partitions and their
location (max 4 primary partitions or
3 primary + 1 Extended + 12 Logical)
• Pointer to partition with bootloader
HD identification
 IDE drives
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Partition identification:
dev/hda
dev/hdb
...
 SCSI
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dev/sda
dev/sdb
...
Note that /dev is not a real directory for
accessing the contents of disks –
it is rather a naming space for all hardware
devices (and their drivers) present in the
system, including keyboard, screen etc.
The contents of disks is made
available in other part of root / hierarchy.
File System Layout
Bootloader can be installed in different locations
(if bootloader not in MBR, the BIOS interprets MBR to find boot partition)
Boot Block
The system’s primary disk unit contains a boot block that contains the
bootstrapping program that loads the OS to memory. This program is invoked by
the computer’s minimal bootstrap program in ROM.
This boot block is often called the Master Boot Record (MBR).
Different operating systems treat the MBR in very different ways. Some are flexible
enough to install a boot loader in the MBR, so that the disk can contain different
OS in different disk partitions. The loader for each OS is then stored at the
beginning of its own partition. Examples: Windows NT/2000/xp boot loader,
Linux lilo and grub.
A “bootable” disk is one on which a boot block has been installed.
Mandatory partitions
 root
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/dev/hda1 (recommended)
This is partition for the actual root / of the UNIX filesystem
 swap
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/dev/hda2 (recommended)
4GB (max with 32bit x86 CPU)
RAM SIZE * 2 (recommended)
This partition is not visible in root / and is used only by kernel for
virtual memory page swapping (“raw” sectors, no structure)
Theoretically swap partition is optional, if enough RAM
Optional partitions or separate HD
 Typically on separate partitions
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/home, /boot, /tmp, /var, /usr
 Reasons for separate partitions
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logical or physical damage
reinstallation (affects only some partitions)
limit overflow effects
better performance
shared via network
File System Types
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VFS
UFS / FFS
NFS
RFS
S5FS
VxFS
JFS
CFS
EXT2/EXT3
GFS
ReiserFS
XFS
CXFS
QFS
HFS
NTFS
FAT16/ FAT32
Virtual File System
UNIX File System – used interchangeably with FFS (Fast File System)
Network File System – developed by Sun
Remote File System – developed by AT&T
Original System V file system
Veritas Journaling File System
Journaled File System – AIX
Cluster file system – Tru64
2nd/3rd Extended File System – Linux systems
Global File System – Linux
Journaling file system – Linux
Extended File System – SGI and others
Clustered Extended File System – SGI
64-bit very large file system – Sun Solaris
Hierarchical File System – S/390 UNIX, OS/2, MacOS X
Windows NT/2000/2003
Windows – several versions
File System Support
 Linux can interpret many
file system types,
including;
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EXT2, EXT3,
UFS/FFS,
FAT16, FAT32
NTFS (read-only),
HPFS
ISO9660, UDF, UFS, etc.
 Win32 can interpret a few
file system types,
including;
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FAT16, FAT32
NTFS
Creating Partitions: GNU Parted
Notes:
1.
2.
3.
4.
5.
6.
For ext2, ext3 and reiserfs: the start of the partition must stay fixed.
For ext2, ext3: the partition you copy to must be bigger or exactly the same size as the partition you copy from.
For ext2 and ext3: the checking is limited to ensuring the resize and copy commands will be ok.
For fat: the size of the new partition after resizing or copying is restricted by the cluster size. Parted can shrink
the cluster size, so you can always shrink your partition. However, if you can't use FAT32 for some reason, you
may not be able to grow your partition.
Parted supports both FAT16 and FAT32. Parted can convert file systems between FAT16 and FAT32, if
necessary.
Reiserfs support is enabled if you install libreiserfs, available at http://reiserfs.osdn.org.ua. (It is likely to be
available soon from http://www.namesys.com)
BSD Versions
 FreeBSD - Focusing on features and ease of use
 Darwin (OS X) - Focusing on the desktop and multimedia
with use of the Apple's Aqua Interface
 NetBSD - Focusing on portability
 OpenBSD - Focusing on security
 PicoBSD - Focusing on size (extremely small)
 DragonflyBSD - Focusing on new computing paradigms
Linux Distributions
 Debian GNU/Linux (Xandros, Knopix,...)
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a free operating system that provides almost 4000 software packages for six
architectures (Intel, Motorola, Alpha, SPARC, PowerPC, ARM) and is developed
entirely by volunteers over the Internet
 Fedora/RedHat
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a Red-Hat-sponsored and community-supported open source project. The goal of
The Fedora Project is to work with the Linux community to build a complete, general
purpose operating system exclusively from free software. Development will be done
in a public forum
 Mandrake Linux
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a friendly Linux Operating System which specializes in ease-of-use for both servers
and the home/office. It is freely available in many languages throughout the world
 Slackware
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a long running Linux distribution that descends from the SLS Distribution
 SuSE Linux
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an extremely popular distro that features excellent documentation, thousands of
applications on a DVD/CD-ROM set
 Gentoo Linux
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an optimized GNU/Linux distribution featuring 5 different pgcc-optimized builds,
including Intel Pentium, Pentium Pro/II/III and AMD K6 optimized
Citi brīvi pieejami Unix
 Solaris 10
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x64/x86
% isainfo -v
 64-bit amd64 applications
 32-bit i386 applications
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SPARC
 Darwin
 Minix
Unix Instalacija
no CD/DVD
Installing NetBSD
Installation
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you should decide the installation media that you will use; you
can choose between:
FTP
NFS
CD-ROM/DVD
floppy disc
unmounted filesystem
local directory
Installing NetBSD
 Geometries
The installation program mentions two types of hard disk geometries; you should
understand what they mean:
 real geometry
 BIOS geometry
 real geometry is the real geometry of the hard disk, detected by the system.
 BIOS geometry is the geometry used by the BIOS and it could be different from the
real one (for example, BIOS could remap the disk using LBA).
 Example real: 6232 cyl, 16 heads, 63 sec
 Example BIOS: 779 cyl, 128 heads, 63 sec (LBA)
 As you can see the BIOS remaps the disk using LBA, effectively reducing the
number of cylinders and increasing the number of tracks (but the result is the same:
6232 * 16 = 779 * 128 = 99712). A sector contains 512 bytes, which means that the
disk size is 6232 * 16 * 63 * 512 = 3 GB. NetBSD does not need to remap the disk
geometry (and in fact won't do it). During the installation it is possible to change
manually the geometry if sysinst got it wrong.
Partitions
Installing NetBSD
Installing NetBSD
Hard disk space requirements
 The space required by a NetBSD installation
depends on the planned use (e.g. server or
workstation). For example, consider a home
desktop system with a 420 MB hard disk (rather
small by today's standards) with X, the kernel
sources and some applications (Netscape, ...). The
swap partition is 32 MB.
Installing NetBSD
Creating the installation floppy
 If you create the boot floppy in a Unix
environment, you can use the dd command. For
example:
# cd i386/installation/floppy
# dd if=boot.fs of=/dev/fd0a bs=36b
Installing NetBSD
Beginning the installation
Installing NetBSD
The main menu of the installation program
Installing NetBSD
Confirming you want to install NetBSD
Installing NetBSD
Choosing a hard disk
Installing NetBSD
Full or custom installation
Installing NetBSD
Selecting distribution sets
Installing NetBSD
Choosing the partitioning scheme
Installing NetBSD
fdisk
Installing NetBSD
Installing the boot selector
Installing NetBSD
The disklabel editor
Installing NetBSD
Installation media
Installing NetBSD
System configuration
Installing NetBSD
Reboot the system to finish installation
Linux
Devices
In Linux, partitions are represented by
device files. These are phoney files located
in /dev. Here are a few entries:
brw-rw---- 1 root disk 3, 0 May 5 1998 hda
brw-rw---- 1 root disk 8, 0 May 5 1998 sda
crw------- 1 root tty 4, 64 May 5 1998 ttyS0
Linux
Device names
 IDE controller naming
convention
drive name
drive controller
drive number
/dev/hda
/dev/hdb
/dev/hdc
/dev/hdd
1
2
1
2
1
1
2
2
Linux
partition names
drive name
drive controller drive number
partition type
partition
number
/dev/hda1
1
1
Primary
1
/dev/hda2
1
1
Primary
2
/dev/hda3
1
1
Primary
3
/dev/hda4
1
1
Swap
NA
/dev/hdb1
1
2
Primary
1
/dev/hdb2
1
2
Primary
2
/dev/hdb3
1
2
Primary
3
/dev/hdb4
1
2
Primary
4
Linux
Logical Partitions
drive name
drive controller drive number
partition type
partition
number
/dev/hdb1
1
2
primary
1
/dev/hdb2
1
2
extended
NA
/dev/hda5
1
2
logical
2
/dev/hdb6
1
2
Logical
3
Linux
Partition Types
 Foreign Partition Types
 Primary Partitions
 Logical Partitions
 Swap Partitions
Linux
Partitioning requirements
For the Boot Drive: If you want to boot your
operating system from the drive you are about to
partition, you will need:
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A primary partition
One or more swap partitions
Zero or more primary/logical partitions
For any other drive:
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One or more primary/logical partitions
Zero or more swap partitions
Linux
File Systems
Everything in your linux file system can go in the same (single) partition. However, there are
circumstances when you may want to restrict the growth of certain file systems. For example, if
your mail spool was in the same partition as your root fs and it filled the remaining space in the
partition, your computer would basically hang.
 /var - This fs contains spool directories such as those for mail and printing. In addition, it
contains the error log directory. If your machine is a server and develops a chronic error, those
msgs can fill the partition. Server computers ought to have /var in a different partition than /.
 /usr - This is where most executable binaries go. In addition, the kernel source tree goes
here, and much documentation.
 /tmp - Some programs write temporary data files here. Usually, they are quite small. However,
if you run computationally intensive jobs, like science or engineering applications, hundreds of
megabytes could be required for brief periods of time. In this case, keep /tmp in a different
partition than /.
 /home - This is where users home directories go. If you do not impose quotas on your users,
this ought to be in its own partition.
 /boot - This is where your kernel images go. See discussion above for placement on old
systems.
Linux
Swap Partitions
 Split the swap space across multiple drives, or at
least on the drive you write to least.
 Put each swap partition on the outer tracks.
Resources
1. http://www.netbsd.org/guide/en/
2. http://www.tldp.org/HOWTO/Partition/
3.ftp://ftp.slackbook.org/pub/slackbook/
slackbook-2.0.pdf
Environment variables
#include <stdlib.h>
extern char **environ;
int main(int argc,char *argv[]) {
int i;
for (i=0;environ[i]!=NULL;i++){
printf("%s\n",environ[i]);
}
return(0);
}
Environment variables
#include <stdlib.h>
int main(int argc,char *argv[]){
if (argc==1){
printf("Nav neviena argumenta\n");
return(1);
} else if (argc>2) {
printf("argc > 2\n");
return(1);
} else {
printf("%s=%s",argv[1],getenv(argv[1]));
}
return(0);
}
Environment variables
#include <stdlib.h>
extern char **environ;
int main(int argc,char *argv[]){
int i;
if (argc==1){
printf("Nav neviena argumenta\n");
return(1);
} else if (argc>2) {
printf("argc > 2\n");
return(1);
} else {
putenv(argv[1]);
}
for (i=0;environ[i]!=NULL;i++){
printf("%s\n",environ[i]);
}
return(0);
}
Environment variables
#include <stdlib.h>
extern char **environ;
int main(int argc,char *argv[]){
int i;
if (argc==1){
printf("Nav neviena argumenta\n");
return(1);
} else if (argc>2) {
printf("argc > 2\n");
return(1);
} else {
unsetenv(argv[1]);
}
for (i=0;environ[i]!=NULL;i++){
printf("%s\n",environ[i]);
}
return(0);
}
Exec
#include <stdlib.h>
int main(int argc,char *argv[]){
printf("execl() system call\n");
execl("/bin/echo","echo","Test1.1","Test1.2",NULL);
return(0);
}
Exec
#include <stdlib.h>
#include <stdio.h>
int main(int argc,char *argv[]){
printf("execl() system call testing\n");
fflush(stdout);
execl("/bin/echo","echo","Test1.1","Test1.2",NULL);
return(0);
}
Fork
#include <stdlib.h>
#include <sys/types.h>
#include <unistd.h>
int main(int argc,char *argv[]){
pid_t pid;
printf("start test\n");
pid=fork();
printf("Return value %d\n",pid);
sleep(1);
return(0);
}
Fork
#include <stdlib.h>
#include <sys/types.h>
#include <unistd.h>
#include <errno.h>
pid_t pid;
int main(int argc,char *argv[]){
pid=fork();
if(pid==-1) {
printf("Error creating new process\n");
return(errno);
}
if(pid==0){
printf("Child\n");
sleep(10);
return(0);
}
if(pid!=0){
wait();
printf("Parent\n");
return(0);
}
}
Fork
#include <stdlib.h>
#include <sys/types.h>
#include <unistd.h>
#include <errno.h>
pid_t pid;
int main(int argc,char *argv[]){
pid=fork();
if(pid==-1) {
printf("Error creating new process\n");
return(errno);
}
if(pid==0){
printf("Child\n");
execl("/bin/ls","ls","-l","/",NULL);
sleep(10);
return(0);
}
if(pid!=0){
wait();
printf("Parent\n");
return(0);
}
}
Signal
#include <stdlib.h>
#include <signal.h>
int i;
void sighandler(){
printf("Catched signal\n");
printf("Reset i value\n");
i=0;
}
int main(int argc,char *argv){
struct sigaction sact;
sact.sa_handler=sighandler;
sigaction(SIGINT,&sact,NULL);
for(i=0;;i++){
printf("%d\n",i);
sleep(3);
}
return(0);
}
Signal
#include <stdlib.h>
#include <signal.h>
int i;
void sighandler(){
printf("SIGHUP signal\n");
printf("Reset i value\n");
i=0;
}
int main(int argc,char *argv){
struct sigaction sact1;
struct sigaction sact2;
sact1.sa_handler=SIG_IGN;
sact2.sa_handler=sighandler;
sigaction(SIGINT,&sact1,NULL);
sigaction(SIGHUP,&sact2,NULL);
for(i=0;;i++){
printf("%d\n",i);
sleep(3);
}
return(0);
}
#include <stdlib.h>
#include <signal.h>
Signal
int i;
void sighandler(){
printf("SIGHUP signal\n");
printf("Reset i value\n");
i=0;
}
int main(int argc,char *argv){
struct sigaction sact2;
sact2.sa_handler=sighandler;
sigaction(SIGHUP,&sact2,NULL);
for(i=0;;i++){
printf("%d\n",i);
sleep(1);
if(i>=10){
if(raise(SIGHUP)!=0){
printf("Problem send signal to current process\n");
}
}
}
return(0);
}