yolinux tutorial linux system configuration and administration.mht

linux下c++编程的好文章

/var/log/mailman/qrunner
python  18580 mailman    6u   REG    3,5  657 486746 =
/var/log/mailman/qrunner
python  18581 mailman    6u   REG    3,5  657 486746 =
/var/log/mailman/qrunner
python  18582 mailman    6u   REG    3,5  657 486746 =
/var/log/mailman/qrunner
python  18583 mailman    6u   REG    3,5  657 486746 =
/var/log/mailman/qrunner
python  18584 mailman    6u   REG    3,5  657 486746 =
/var/log/mailman/qrunner=20
    </PRE></DD></DL>The process attached to an open file can be killed=20
          using the command <TT><A=20
          =
href=3D"http://node1.yo-linux.com/cgi-bin/man2html?cgi_command=3Dfuser">f=
user</A>=20
          -ki <I>filename</I></TT>=20
          <P></P>
          <LI>List all open files on system: <TT>lsof</TT> <BR>(Long =
list)=20
          <P></P>
          <LI>List all files opened by user: <TT>lsof -u =
<I>user-id</I></TT>=20
          <P></P>
          <LI>The commands <TT>netstat -punta</TT> and <TT>socklist</TT> =
will=20
          list open network connections. Use the command <TT>lsof -i=20
          TCP:<I>port-number</I></TT> to see the processes attached to =
the port.=20
          Example:=20
          <DL>
            <DD><PRE><B>[root@node DIR]#</B> lsof -i TCP:389
COMMAND   PID USER   FD   TYPE  DEVICE SIZE NODE NAME
slapd    5927 ldap    6u  IPv4 7560023       TCP *:ldap (LISTEN)
slapd    5928 ldap    6u  IPv4 7560023       TCP *:ldap (LISTEN)
slapd   21185 ldap    6u  IPv4 7560023       TCP *:ldap (LISTEN)
slapd   21186 ldap    6u  IPv4 7560023       TCP *:ldap (LISTEN)
slapd   21193 ldap    6u  IPv4 7560023       TCP *:ldap (LISTEN)
</PRE></DD></DL>This shows that the command <TT>slapd</TT> running=20
          under user id <TT>ldap</TT> is running five process connected =
to port=20
          389. </LI></UL></DD></DL>
      <UL></UL>
      <P><B>Restricting user resources:</B>=20
      <DL>
        <DD>
        <UL><A name=3DULIMIT></A>
          <LI><B>ulimit:</B> (bash shell command)=20
          <P>Shell and process resources may be controlled and reported =
using=20
          the <TT>ulimit</TT> command. Display the limits of a shell =
using the=20
          bash command "<TT>ulimit -a</TT>". Limits can be set for the =
number of=20
          open files and processes, memory and virtual memory etc.=20
          <P></P>
          <LI>See limits assigned in <TT>/etc/security</TT> (<A=20
          =
href=3D"http://www.yolinux.com/TUTORIALS/LinuxTutorialSysAdmin.html#RESTR=
ICTUSERS">discussed=20
          below</A>)=20
          <P></P>
          <LI>Modify process scheduling priority: Range goes from -20 =
(highest=20
          priority) to 19 (lowest).=20
          <UL>
            <LI>Lower scheduling priority (runs slower and less likely =
to slow=20
            you down.) <BR><TT>nice -n 19 <I>program-to-launch</I></TT>=20
            <BR>Default for "<TT>nice -n</TT>" is 10=20
            <LI>Show default for any process: <TT>nice =
<I>executable</I></TT>=20
            <BR>Shows nice value to be used if run. </LI></UL>
          <P></P></LI></UL></DD></DL>
      <P><A name=3DFILESYSTEMS></A>
      <P>
      <HR SIZE=3D5>

      <TABLE cellSpacing=3D0 cellPadding=3D2 width=3D"100%" border=3D0>
        <TBODY>
        <TR bgColor=3D#ffcc33>
          <TD><B><BIG>Filesystems and Storage=20
      Devices:</BIG></B></TD></TR></TBODY></TABLE>
      <P><B>Hard Drive Info:</B>=20
      <DL>
        <DD>
        <TABLE>
          <TBODY>
          <TR>
            <TD><A=20
              =
href=3D"http://node1.yo-linux.com/cgi-bin/man2html?cgi_command=3Ddf">df=20
              -k</A> </TD>
            <TD>report filesystem disk space usage. (-k reports in=20
          Kbytes)</TD></TR>
          <TR>
            <TD><A=20
              =
href=3D"http://node1.yo-linux.com/cgi-bin/man2html?cgi_command=3Ddu">du=20
              -sh</A> </TD>
            <TD>Calculates file space usage for a given directory. (and=20
              everything under it) (-s option summarizes)</TD></TR>
          <TR>
            <TD><A=20
              =
href=3D"http://node1.yo-linux.com/cgi-bin/man2html?cgi_command=3Dmount">m=
ount</A>=20
            </TD>
            <TD>Displays all mounted devices, their mount point, =
filesystem,=20
              and access. Used with command line arguments to mount file =

            system.</TD></TR>
          <TR>
            <TD>cat /proc/filesystems </TD>
            <TD>Display filesystems currently in use.</TD></TR>
          <TR>
            <TD>cat /proc/mounts </TD>
            <TD>Display mounted filesystems currently in use.</TD></TR>
          <TR>
            <TD><A=20
              =
href=3D"http://node1.yo-linux.com/cgi-bin/man2html?cgi_command=3Dshowmoun=
t">showmount</A>=20
            </TD>
            <TD>Displays mount info for NFS filesystems.</TD></TR>
          <TR>
            <TD>cat /proc/swaps</TD>
            <TD>Displays swap partition(s) size, type and quantity =
used.</TD></TR>
          <TR>
            <TD>cat /proc/ide/hda/<I>any-file</I></TD>
            <TD>Displays disk information held by=20
        kernel.</TD></TR></TBODY></TABLE></DD></DL>
      <P><B>Adding an extra hard drive:</B> (<A=20
      =
href=3D"http://www.yolinux.com/TUTORIALS/LinuxTutorialAdditionalHardDrive=
.html">See=20
      commands and dialog of adding a second IDE hard drive</A>)=20
      <OL>
        <LI><TT><A=20
        =
href=3D"http://node1.yo-linux.com/cgi-bin/man2html?cgi_command=3Dfdisk">f=
disk</A>=20
        /dev/<I>&lt;drive&gt;</I></TT> <B>- Allocate drive space and =
register=20
        info on the partition table.</B> (Option "n"/"p", then "w" to =
write.)=20
        <BR>Also see: <A=20
        =
href=3D"http://node1.yo-linux.com/cgi-bin/man2html?cgi_command=3Dsfdisk">=
sfdisk</A>=20
        - <A=20
        =
href=3D"http://node1.yo-linux.com/cgi-bin/man2html?cgi_command=3Dcfdisk">=
cfdisk</A>=20

        <LI><TT><A=20
        =
href=3D"http://node1.yo-linux.com/cgi-bin/man2html?cgi_command=3Dmkfs">mk=
fs</A>=20
        -t ext3 /dev/<I>&lt;drive&gt;</I></TT> <B>- Create file =
system.</B> (RH=20
        7.1 and earlier use ext2, RH 7.2-8.0 use ext3)=20
        <LI><TT><A=20
        =
href=3D"http://node1.yo-linux.com/cgi-bin/man2html?cgi_command=3Dmount">m=
ount</A>=20
        -t ext3 /dev/<I>&lt;drive's device name&gt;</I> /<I>&lt;home2 or =
some=20
        suitable directory&gt;</I></TT> <B>- Mount the drive</B> =
<BR>Mount a raw=20
        ISO file: <TT>mount -t iso9660 -o loop=20
        /home/<I>user1</I>/RedHat-9.0-i386-Disk1.iso /mnt/iso-1</TT> =
<BR>(Fstab=20
        entry: <TT>/home/<I>user1</I>/RedHat-9.0-i386-Disk1.iso =
/mnt/iso-1=20
        iso9660 loop,ro 0 3</TT>) </LI></OL>
      <P>Also see: <A=20
      =
href=3D"http://node1.yo-linux.com/cgi-bin/man2html?cgi_command=3Dmkefs">m=
kefs=20
      man page</A>=20
      <P>Where the drive is /dev/hdb or some device as conforms to the =
Linux=20
      device names:=20
      <P>IDE drives are referred to as hda for the first drive, hdb for =
the=20
      second etc... IDE uses separate ribbon cables for primary and =
secondary=20
      drives. The partitions on each drive are referred numerically. The =
first=20
      partition on the first drive is referred to as hda1, the second as =
hda2,=20
      the third as hda3 etc ...=20
      <P>Linux IDE naming conventions:=20
      <DL>
        <DD>
        <TABLE cellPadding=3D2 border=3D1>
          <TBODY>
          <TR bgColor=3D#dfdfdf>
            <TH>Device</TH>
            <TH>Description</TH>
            <TH>Configuration</TH></TR>
          <TR bgColor=3D#eeeeee>
            <TD>/dev/hda</TD>
            <TD>1st (Primary) IDE controller</TD>
            <TD>Master</TD></TR>
          <TR bgColor=3D#eeeeee>
            <TD>/dev/hdb</TD>
            <TD>1st (Primary) IDE controller</TD>
            <TD>Slave</TD></TR>
          <TR bgColor=3D#eeeeee>
            <TD>/dev/hdc</TD>
            <TD>2nd (Secondary) IDE controller</TD>
            <TD>Master</TD></TR>
          <TR bgColor=3D#eeeeee>
            <TD>/dev/hdd</TD>
            <TD>2nd (Secondary) IDE controller</TD>
            <TD>Slave</TD></TR></TBODY></TABLE></DD></DL>
      <P>Note: SCSI disks are labeled /dev/sda, sdb, etc... For more =
info see <A=20
      =
href=3D"http://www.yolinux.com/TUTORIALS/LinuxTutorialSCSI.html">SCSI=20
      info</A>.=20
      <P>Use the command <TT>cat /proc/partitions</TT> to see full list =
of disks=20
      and partitions that your system can see.=20
      <P>See Linux devices:=20
      <UL>
        <LI>Kernel 2.4: (Red Hat 7.1+)=20
        <UL>
          <LI><A=20
          =
href=3D"file:///usr/src/linux-2.4/Documentation/devices.txt">file:/usr/sr=
c/linux-2.4/Documentation/devices.txt</A>=20
          - (local file) </LI></UL>
        <LI>Kernel 2.2: (Red Hat 7.0-)=20
        <UL>
          <LI><A=20
          =
href=3D"file:///usr/src/linux/Documentation/devices.txt">file:/usr/src/li=
nux/Documentation/devices.txt</A>=20
          (local file) - H. Peter Anvin </LI></UL></LI></UL>
      <P>To make the drive a permanent member of your system and have it =
mount=20
      upon system boot, add it to your <TT>/etc/fstab</TT> file which =
holds all=20
      the file system information for your system. See <A=20
      =
href=3D"http://node1.yo-linux.com/cgi-bin/man2html?cgi_command=3Dfstab">m=
an=20
      page for fstab</A>.=20
      <P>Example of existing /etc/fstab file:=20
      <DL>
        <DD>
        <TABLE cellSpacing=3D1 cellPadding=3D4 width=3D"100%" =
bgColor=3D#000000=20
border=3D1>
          <TBODY>
          <TR bgColor=3D#c0c0c0>
            <TD><PRE>/dev/sdb6               /                       =
ext2    defaults        1 1
/dev/sdb1               /boot                   ext2    defaults        =
1 2
/dev/cdrom              /mnt/cdrom              iso9660 =
noauto,user,users,ro 0 0
/dev/fd0                /mnt/floppy             auto    noauto,owner    =
0 0
none                    /proc                   proc    defaults        =
0 0
none                    /dev/pts                devpts  =
gid=3D5,mode=3D620  0 0
/dev/sdb5               swap                    swap    defaults        =
0 0
</PRE></TD></TR></TBODY></TABLE></DD></DL>
      <P>Add SCSI drive by adding line:=20
      <DL>
        <DD>
        <TABLE cellSpacing=3D1 cellPadding=3D4 width=3D"100%" =
bgColor=3D#000000=20
border=3D1>
          <TBODY>
          <TR bgColor=3D#c0c0c0>
            <TD><PRE>/dev/sdc1               /home2                  =
ext2    defaults        1 2
</PRE></TD></TR></TBODY></TABLE></DD></DL>
      <P>At this point one may optionally check the file system created =
with the=20
      command: <TT>fsck /dev/sdc1</TT>=20
      <P>Note that <TT>fsck</TT> is NOT run against a mounted file =
system.=20
      Unmount it first if necessary. (umount) Also see the man page for: =

      <UL>
        <LI><A=20
        =
href=3D"http://node1.yo-linux.com/cgi-bin/man2html?cgi_command=3Dcfdisk">=
cfdisk</A>=20
        - Curses based disk partition table manipulator. (very nice)=20
        <LI><A=20
        =
href=3D"http://node1.yo-linux.com/cgi-bin/man2html?cgi_command=3Dfdisk">f=
disk</A>=20
        - Manipulate/configure the partition table.=20
        <LI><A=20
        =
href=3D"http://node1.yo-linux.com/cgi-bin/man2html?cgi_command=3Dsfdisk">=
sfdisk</A>=20
        - Manipulate/configure the partition table.=20
        <LI><A=20
        =
href=3D"http://node1.yo-linux.com/cgi-bin/man2html?cgi_command=3Dfsck">fs=
ck</A>=20
        </LI></UL><A name=3DMOUNTCD></A>
      <P>
      <HR>

      <P><B>Mounting other file systems:</B> (locally attached drives)=20
      <P>
      <UL>
        <LI>Mounting a CD: <TT>mount -r -t iso9660 /dev/cdrom =
/mnt/cdrom</TT>=20
        <BR>Un-Mount the CD-ROM: <TT>umount /dev/cdrom</TT> <B>(No "n" =
in=20
        <TT>umount</TT>)</B>=20
        <P>This command should work for a Red Hat installation. Other=20
        distributions may require the following set-up: <PRE>        ln =
-sf /dev/hdc /dev/scd0     <B><I>Reference SCSI device directly.</I></B>
        <B>OR</B>
        ln -sf /dev/hdc /dev/cdrom     <B><I>A more typical =
system</I></B>

        cd /mnt
        mkdir cdrom
        mount -t iso9660 -o ro /dev/cdrom /mnt/cdrom

    </PRE>
        <P>Don't forget to un-mount the CD with <TT>umount =
/mnt/cdrom</TT>=20
        <BR><B><FONT color=3D#ff0000>[Potential Pitfall]:</FONT></B> =
There is NO=20
        "N" in umount!!!=20
        <P>For trouble shooting your CD see your kernel documentation:=20
        <UL>
          <LI>Kernel 2.4: <A=20
          =
href=3D"file:///usr/src/linux-2.4/Documentation/ide.txt">file:/usr/src/li=
nux-2.4/Documentation/ide.txt</A>=20
          (local file)=20
          <LI>Kernel 2.2: <A=20
          =
href=3D"file:///usr/src/linux/Documentation/ide.txt">file:/usr/src/linux/=
Documentation/ide.txt</A>=20
          (local file) </LI></UL>
        <P></P>
        <LI><A=20
        =
href=3D"http://www.yolinux.com/TUTORIALS/LinuxTutorialRedHatInstallation.=
html#WINPARTITION">Mounting=20
        a Windows partition.</A>=20
        <P></P>