LINUX Command Notes
Linux System Information and Utilities NOTES
ADMINISTRATIVE and SECURITY-----------------------------------------------------
To change root password when forgotten. Get into single usermode and issue passwd root.
Type 'b' at GRUB bootloader menu.
Get into single usermode.
Append SINGLE to kernel line using editor 'e'.
Get back to GRUB by entering 'b'.
Issue passwd root at prompt sb-2.xx#
Exit and reboot.
commands:
hostname
visudo
useradd
usermod
userdel
users
who
passwd
find / -user -print
du -s /home/* disk usage
chmod rwx change access permissions (4-read, 2-write, 1-execute)
chown change owner of files
uid displays UID and GID numbers of username
data:
/etc/sudoers semi-priv users defs
/etc/passwd lists all users with logins
AUTOMATION --------------------------------------------------------------------
commands:
chkconfig --list | grep smb shows status of smb automation
chkconfig --add adds task and builds links in /etc/rcn.d directories
chkconfig --del deletes task and removes links in /etc/rcn.d directories
chkconfig --level n smb on|off sets runlevel n either on or off
serviceconf & brings up Service Configuration task autostart panel
runlevel shows current (and maybe last) runlevel
telinit n n=0,1,2,3,4,5,6 init command will bring system to runlevel n
service restart|stop|start|status
crontab fname.crontab start time utility using configuration file
data:
/etc/sysctl.conf modify kernel parameters at runtime and boot time,
the parameters available are found under /proc/sys/
/etc/inittab entry id:X:initdefault: change 'X' from '3' to '5'.
fname.crontab cron entries for regularly scheduled tasks
Field Description Valid Values
1 Minute,min,, 0-59
2 Hour,hr,, 0-23
3 Day of Month,, 0-31
4 Month,, 1-12
5 Day of Week,, 0-7
6 pathname of task module
7 pathname of task parms
AUTOMATIC FILE SERVICES (autofs) -----------------------------------------------
data:
/etc/auto.master automount targets
/etc/auto.misc automount definitions
commands:
/sbin/service autofs start | stop | restart | status | reload
BASH and Scripts ---------------------------------------------------------------
debug:
bash -x
bash -v
BOOT ---------------------------------------------------------------------------
Install GRUB Boot Loader on target disk:
/sbin/grub-install /dev/hda --recheck
/sbin/grub-install /dev/hda --root-directory=/boot '(hdnumber)'
Correct GRUB Boot Loader during RESCUE:
chroot /mnt/sysimage
grub
setup floppy:
(use makeboot under control of Linux)
reboot
root (fd0)
setup (fd0)
quit
setup MBR for primary (not secondary) disk drive:
reboot
find /boot/grub/stage1
root (hd0,x) where x is partid 0,1,...n
setup (hd0) important: not hd0,x otherwise will write on partid not MBR.
quit
from disk starting with floppy:
reboot
find /boot/grub/stage1
kernel (hd1,0)/vmlinuz-2.4.18-14 root=/dev/hdb1 ro
boot
C++ COMPILING and EXECUTION -----------------------------------------------------
commands:
gcc -Wall -Werror -Wno-deprecated -o outputname inputname.c C compiling
g++ -Wall -Werror -Wno-deprecated -o outputname inputname.C C++ compiling
./outputname Execution
time ./outputname Timed Execution
rpm --query glibc Queries the glibc version and level
rpm --query gcc Queries the C-compiler version and level
DISK MANAGEMENT ----------------------------------------------------------------
commands:
mount /mnt/cdrom
mount /mnt/cdrom1
ls -dl
df -h display diskspace usage
mkdir make directory
CD:
cdrecord -scanbus
cdrecord -v speed=2 dev=0,0,0 -data /home/scanner/checks/
note: dev=x,y,z where x=drive,y=SCSI_id, y=Logical_Unit_Number
cdrecord -v speed=2 dev=0,0,0 blank=all
cdrecord -v speed=2 dev=0,0,0 blank=fast only toc and directory pointers
cdrecord -v dev=0,0 speed=0 -data /home/gjcullen/temp/pserver.jar
mkisofs -U -o /var/tmp/gjc.back /home/gjcullen/mydirectory all ISO stds off
mkisofs -U -m photos -o /var/tmp/gjc.back /home/gjcullen/mydirectory with photos excl
mkisofs -o /var/tmp/gjc.back /home/gjcullen/mydirectory
cdrecord -v speed=2 dev=0,0,0 blank=all -data /var/tmp/gjc.back
cdrecord -v speed=2 dev=0,0,0 blank=fast -data /var/tmp/gjc.back
DVD:
dvdrecord -scanbus
dvcrecord -v speed=4 dev=0,0,0 -data /home/scanner/checks/
DISK MANIPULATION and MAINTENANCE ----------------------------------------------
ls -dl
df -h diskspace usage
fdisk -l view layout
mkdir to match mountpoint in /etc/fstab table for new disk.
rm removes file with prompting
rm -f -r removes files (directories) recursively with no prompting
du -s /home/* disk usage
Partitioning utilities
fdisk /dev/hdx
parted /dev/hdx
Copying partitions on current device
parted cp source_device from_partno to_partno
Formatting partitions
/sbin/mkfs -t ext3 /dev/hdbx
mkfs -t ext3 /dev/fd0 format diskette to Linux format
mkfs -t vfat /dev/fd0 format diskette to Windows format
Labelling partitions
e2label /dev/hdbx /newname Re-labelling to newname
Formatting diskettes
fdformat /dev/fd0H1440
mke2fs /dev/fd0
mount -t ext2 /dev/fd0 /mnt/floppy
*** do something ***
umount /mnt/floppy
Mounting linux hard disks
/sbin/mount -t ext3 /dev/hdxy /some_name/ x=a,b,c,d,... y=1,2,3,...
Make filesystem on linux hard disks
mkfs.ext3 /dev/hdxy x=a,b,c,d,... y=1,2,3,...
DESKTOP PROBLEMS ---------------------------------------------------------------
startx
XFree96 -configure
XFree86 -xf86config /root/XF86Config.new
Garbled... Ctrl+Alt+F2, get Login, Pass, SHutdown X servy by typing init 3
then run XF86Config
Dynamic Host Configuration Protocol (DHCP) -------------------------------------
commands:
/etc/init.d/dhcpd start | start | stop
/sbin/chkconfig dhcpd on | off
data:
/etc/dhcpd.conf
/var/lib/dhcp/dhcpd.leases
DOMAIN NAME SERVICES (DNS) -----------------------------------------------------
commands:
/etc/init.d/named restart | start | stop
/sbin/service/named restart | start | stop | restart | status
/sbin/chkconfig named on | off
host replacement for nslookup of IP address(es)
data:
/etc/named.conf DNS parameters
/etc/resolv.conf IP addresses of DNS servers
/var/named/*
EMAIL --------------------------------------------------------------------------
commands:
data:
/etc/sendmail.cf
ENVIRONMENTAL VARIABLES --------------------------------------------------------
commands:
env display all environmental variables in effect
CLASSPATH=$CLASSPATH:
export ie. export CLASSPATH
setenv string
set shows all variables and settings
echo $
FILE COMPRESSION----------------------------------------------------------------
commands:
zip, unzip, tar, gzip, gunzip
tar -cvf archive_name files... make archive file
tar -xvf archive_name pathname extract archived files
tar -zxvf archive_name pathname extract archived files from GZIPped file
tar cf ‐ . | zip backup ‐ accept from piped input and compress
unzip ‐p backup | tar xf ‐ recover files
gzip tarfile_name compress zipped files
gzip -d archive_name uncompress zipped files
zip pserver.zip /home/pserver/*.*
unzip pserver.zip -d /newhome/pserver/
GREP ---------------------------------------------------------------------------
count ls -s -l -S | grep 'something' -c
GHOSTSCRIPT --------------------------------------------------------------------
gs -h
rpm -Uv ghostscript-7.07-1.i386.rpm
HTTP SERVER --------------------------------------------------------------------
commands:
/etc/init.d/httpd start | stop
/sbin/chkconfig httpd on | off
data:
/etc/httpd/conf/httpd.conf configuration
/var/www/html html pages
/var/log/httpd/access_log access logging
/var/log/httpd/error_log error logging
/etc/hosts list of hosts
INTERRUPT SIGNALS --------------------------------------------------------------
data:
man 7 signal manual page for signals
INFORMATION about SYSTEM -------------------------------------------------------
commands:
uname -a identify system
hostname query the name of the system
hostname change the name of the system
less /etc/passwd show who has accounts on the system
mount shows all mount points in effect
stat shows the status of a particular file
man shows manual pages for command or function
info shows more use information
/sbin/lspci query installed pci hardware devices
/sbin/lsusb query installed usb hardware devices
cat /proc/cpuinfo query CPU processor
dmesg shows wrap-around kernel messages
KERNEL (nucleus) SYSGEN (build) ------------------------------------------------
commands:
cd /usr/src/linux.....
make mrproper
make menuconfig or make xconfig
use as input your last known good config,
save the output config for later input, do not overwrite the input config.
make dep > dep.log 2>&1
make clean
make bzImage > bzimage.log 2>&1
make modules
make modules_install
make install
Check your and /boot/initrd.... and /boot/grub/grub.conf files.
..reboot..
Select new nucleus from GRUB menu.
DONE...
mkinitrd -v /boot/initrd-n.n.n.img x.y.z where x.y.z must be module subdirectory
in /lib/modules/x.y.z
make dep && make clean bzImage modules modules_install
mount /boot
cp /usr/src/linux/arch/i386/boot/bzImage /boot/
reboot
data:
/usr/src/xxxxx
MAINTENANCE --------------------------------------------------------------------
commands:
uname -r show OS release level
uname -v show time of last kernel build
data:
MESSAGING ----------------------------------------------------------------------
commands:
wall will send message to all logged on users
MONITORING----------------------------------------------------------------------
commands:
top real time task and system performance monitor
ps -e list of all process ids
ps aux | less list of process ids
ps -e -f -m | grep list of process ids and all threads for something
who -umH who is on this terminal
jobs what jobs are running in background
watch df (or ls -l) monitor disk usage in realtime
kill terminate a process
iostat
vmstat
MOZILLA -------------------------------------------------------------------------
data:
/usr/local/mozilla/
plugins using gcc32 coding for java
NETWORK FILE SERVICES (NFS) ----------------------------------------------------
data:
/etc/export contains accesses and permissions.
requires UDP/TCP port access to 111 (sunrpc), 369 (rpc2portmap) and 2049 (nfs services)
requires PORTMAP daemon
commands:
/etc/rc.d/init.d/nfs start NFS
/sbin/service nfs start | stop | restart | reload | status
/sbin/service nfs reload reloads the nfs permits
exportfs
/usr/sbin/showmount show all users with NFS mounts
/sbin/chkconfig nfs on
/usr/sbin/exportfs -ra reloads exported file system for NFS
cat /etc/services | grep show tasks that are using port
NETWORK ------------------------------------------------------------------------
commands:
nmap -sT -O localhost verify which ports are in use
netstat -anp | grep
lsof -i | grep show port bindings
netstat -r -n query network routing table with resolved names
route query network routing table
dig query network domain name servers
/etc/init.d/network restart | start | stop Restart,etc Network
/usr/sbin/traceroute Show path to ip_address
ping Test connectivity
data:
/etc/sysconfig/network-script/ifcfg-ppp0
/etc/sysconfig/network set GATEWAYDEV to PPP0 | ip.address
/etc/xinetd.conf xinetd configuration file
/etc/xinetd.d/* all xinetd-started services (DISABLE=yes|no)
DIALUP -----
commands:
ps x | grep ppp
/sbin/ifconfig ppp0 show status for modem with IPaddress
/sbin/ifconfig up | down ie. ifconfig ppp0 up
data:
ETHERNET -----
commands:
cat /proc/net/dev
ps x | grep eth
/sbin/ifconfig eth0
/sbin/ifconfig up | down ie. ifconfig ppp0 up
WIN: winipcfg, msconfig, mscnfig
data:
ROUTING and IPTABLES -----
commands:
chkconfig --level 345 iptables on Sets the iptables scripts to start autom at boot time
iptablesflush script to flush all iptables
gjciptables script to reload all iptables
/etc/init.d/iptables restart | start | stop Recycle iptables
/sbin/lsmod | grep ip See if modules used by iptables are loaded
/sbin/iptables
/sbin/iptables -t nat -R POSTROUTING 1 -o eth1 -j MASQUERADE changes chain 1
cp /etc/sysconfig/iptables /etc/sysconfig/iptables.old
/sbin/iptables-save > /etc/sysconfig/iptables
(or service iptables save)
/sbin/iptables -L
/sbin/iptables -L -t nat
service iptables restart|stop|start|status
data:
/etc/sysconfig/iptables Iptables config is saved here
Enable IP Forwarding
/etc/sysctl.conf set net.ipv4.ip_forward = 1
/etc/sysconfig/network/sysctl.conf
/etc/lpd.conf
PORTS -----
commands:
nmap -sT -O localhost
cat /etc/services | grep nnn
netstat -anp | grep nnn
lsof -i | grep nnn
TCPIP and DIALER -----
commands:
/sbin/ifconfig
/sbin/ifconfig ppp0 up | down
ls -l /dev/modem
wvdialconf create
/sbin/route -n
netstat -r
data:
/etc/resolv.conf
/etc/hosts
/etc/host.conf
/etc/nsswitch.conf
/dev/ttys0 (COM1)
/dev/ttys1 (COM2)
/etc/wvdial.conf
/etc/ppp/options
End NETWORK --------------------------------------------------------------------
OPENOFFICE ---------------------------------------------------------------------
Setup User Access
/opt/OpenOffice.org1.1.2/./setup
PRINTING ------------------------------------------------------------------------
commands:
/usr/sbin/lpc
status to check status of printers
enable to enable a printer
disable to disable a printer
start all to start all printers
stop all to start all printers
lpr filename.filext for offline printing
lpr -Plp0 test.data
lp -d file print the file to designated printer
lprm -a all will remove all print from all printers
lprm -Plp0 167 will remove jobid 167 from print queue of lp0
lprm -PHP952C@GJCULLEN nnn will remove jobid nnn from print queue of HP952C
lprm -Plp0 will remove jobs to printer lp0
lpq see print jobs queued
printconf -gui
/usr/sbin/lpc reread
/usr/sbin/checkpc -f check printer attachments
printtool
cat /etc/hosts > /dev/lp0
/sbin/service lpd restart stop start status
/sbin/service cups restart stop start status
/usr/bin/lpstat -t checks all cups printers
Windows IPP client: wpnpins
telnet: POST / HTTP/1.1
data:
/etc/cups/cupsd.conf cups configuration
/etc/cups/client.conf cups client config
/etc/printcap
/var/log/messages
RECOVERY -----------------------------------------------------------------------
commands:
fsck /dev/hdxn -p -y -v for automatic repair
efsck /dev/hdxn -p -y -v for extended automatic repair
REMOTE CONNECTIVITY ------------------------------------------------------------
commands:
from client machine: xhost +remotename
from client machine: telnet -l user loginid
or use exportxhost
at server via telnet: export DISPLAY=remotename:0
at server : xterm -title "Terminal Window from Server"
or use addxhost
delxhost
RPM ----------------------------------------------------------------------------
/usr/bin/redhat-config-packages
commands:
rpm -qa | egrep kernel show all kernel related RPMs installed
strace -f rpm .... trace rpm
mv __db*.* /temp/ save old rpm db files
rpm --rebuilddb -vv rebuild rpm db files
data:
/var/lib/rpm directory
rpm -qip displays information on a package
rpm -Va verify entire system
rpm -qf find package owner of this file
rpm -iv install package
rpm -e remove package
SHUTDOWN------------------------------------------------------------------------
commands:
shutdown
reboot
poweroff
halt shutdown -r now
STORAGE and MEMORY -------------------------------------------------------------
commands:
free
free -m
SQUID --------------------------------------------------------------------------
commands:
ps x | grep squid
/etc/init.d/squid restart | start | stop
data:
/var/log/squid
/etc/squid/squid.conf
SAMBA and SWAT SERVICES ---------------------------------------------------------
commands:
ps x | grep swat
/sbin/service smb restart restart samba server
http://localhost:901 use root for access
testparm smb.conf to sanity check SAMBA printing parameters
smbclient -L yourhostnamedata list shares available on server
smbclient //yourhostname/aservicedata: connect with a UNIX client
C:\> net use d: \\servername\service connect from a DOS client
data:
/etc/xinetd.d/swat
SYSLOG --------------------------------------------------------------------------
commands:
service syslog restart
tail -f /var/log/pppmsg
ifup ppp0
ifdown ppp0
data:
/etc/syslog.conf
modifications:
daemon. * /var/log/pppmsg
local2.* /var.log.pppmsg
Telnet --------------------------------------------------------------------------
commands:
ps x | grep telnet
/etc/init.d/telnetd start | stop | restart | status
telnet interactive terminal connect to another machine
data:
/etc/issue.net change connection banner
/etc/issue change connection banner
UTILITIES -----------------------------------------------------------------------
commands:
unzip -a
zip
dos2unix
CLASSPATH=........:........:.....: $CLASSPATH
xport CLASSPATH
Find data:
find / -name xxxxxxx -print will find member anywhere on system
find / -name -exec -ls -Fla {} \;
whereis will find library if in PATH
/utilities/recover deleted files
locate xxxxxx Locates files and directories that have string xxxxx in them.
USB ----------------------------------------------------------------------------
commands:
modprobe usb-storage ensure that usb modules loaded into storage
data:
/etc/fstab
VSFTP FTP-----------------------------------------------------------------------
commands:
ps x | grep ftp
/etc/init.d/vsftpd start | stop | restart | status
ftp ftp connect to another machine
data:
/etc/vsftpd.conf configuration
/etc/vsftpd.user_list
/etc/xinetd.d/vsftpd
/var/log/vsftpd.log logging data
/etc/hosts.allow hosts and facilities allowed via INET
XINETD --------------------------------------------------------------------------
commands:
ps x | grep xinetd
/etc/init.d/xinetd restart | start | stop
data:
/var/log/squid
/etc/squid/squid.conf
/etc/hosts.deny hosts and facilities denied via INET
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