pwd Get
current directory
ls -l File listing
du -k Get size of all subdirectories in KB
du -m Get size of all subdirectories in MB
cp -r en en.backup Copy directory
recursively to new one
ln -s /u01
newlink Create
a symbolic link
du -S | sort -n | tail
-20 Finding the
largest directories
ls -lR | sort +4n |
tail -20 Finding the
largest files
find . -name
filename.txt Find a
file in hard disk
which java Locate command, display pathname/alias
find / -perm -2 ! -type
l -ls Find all world
writable files
find / -nouser -o
-nogroup -print Find files
with no owner and no group
find . -type f | xargs
grep -n "text" Find
text in string
find . -type f -size
+20000k -exec ls -lh {} \; | awk '{ print $9 ": " $5 }'
find . -size +20000k
-exec du -h {} \;
find . -size +20000k
-exec du -h {} \; | sort -n | more
cat filename.txt List contents of
file
more filename.txt List contents of file, with page pause
tail -f
filename.log List contents of file, with scrolling
head -10
filename.log List
first 10 lines of a file
tail -10
filename.log List
last 10 lines of a file
grep -i text
test.log Search
for "text" in file, case insensitive
grep text
test.log Search for "text" in file, case sensitive
df -k File system in Kb
df -h File
system in MB
df -m File
system in MB
ps -ef View
all processes on system
kill -9 12345 Force kill
process id 12345
killall a.out Kill all
processes
free -m Check
the amount of free memory
ps -efaux View all
processes hierarchically
top Running processes; cpu & memory usage
pstree -p Shows
running processes in tree format
ps -aux | sort +5n |
tail -20 Find processes
that are largest
gzip download.tar Compress file to
.gz file
gunzip
download.tar.gz Uncompress
tar -xvf
download.tar Extract
tar -cvf newfile.tar
*.bmp TAR the files
gtar -xzvf
source.tar.gz onefile.java Extract only one file
gtar -xzvf
webmail*.tar.gz Extract compressed file
gtar -czvf
source.tar.gz directory GTAR +
compress
jar tvf test.jar View contents of
JAR file
jar xvf test.jar Extract contents
of JAR file
netstat -nr Show routing table
netstat -na | grep
7001 | grep LISTEN See if exists process on port 7001
traceroute
200.200.200.23 Traces
route & hops to target ip
tcpdump Dump
traffic on a network
rpm -e --test
anonftp-3.0-9 Not real
uninstall
rpm -i
anonftp-3.0-9.i386.rpm Install RPM package
rpm -q kernel Short kernel
version
rpm -qa Query
the RPM database
rpm -qa | grep
perl Query the RPM for anything
'perl'
rpm -qai Query +
information
rpm -qia Query all
detail
rpm -e
anonftp-3.0-9 Uninstall RPM package
hostname Display
hostname of server
uptime Uptime
of server
uname -a Show
kernel version
uname -r Short
kernel version
dmesg Find
out information
rpm -q kernel Short kernel
version
rpm -qi kernel Detailed kernel
version
nmap localhost Check open ports
alias bdf='df -h' Create alias
alias bdf Query
alias
set -o vi Set
command thing to vi
env Show environment
export
ORACLE_SID=demo Set an environment variable (Bash shell)
setenv ORACLE_SID
demo Set an
environment variable (C shell)
echo $CLASSPATH Query classpath
environment
history Show
history
umask 027 Default
create permissions of 750
echo $SHELL See what
shell you are running
export PS1='\u:$PWD>
' Set prompt
shutdown -h 10 Shutdown and
halt in 10 seconds
shutdown -r 10 Shutdown and
reboot in 10 seconds
poweroff Power off
halt Halt
id Information on current user
id webuser Information
on user 'webuser'
groups Groups of current user
groups webuser Groups of user
'webuser'
gpasswd Administer the /etc/group file
last -20 Show last
20 logged in users
useradd, usermod,
userdel User admin
commands
groupadd, groupmod,
groupdel Group admin
commands
top Realtime
iostat 2 CPU and
IO stats every 2 seconds
vmstat 5 System
statistics every 5 seconds
ll ; ll Run
multiple commands using ;
ulimit Set or get
limits on system resources
ulimit -Sa Check if
shell has limits on file size
ulimit -Ha Check if
shell has limits on file size
chkconfig --list Query runlevels
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