General Linux Commands for DBAs
Command
|
Description
|
Examples
|
pwd
|
Displays current
working directory
|
$ pwd
/usr/kalyan
|
ls
|
List the current
directory contents
|
$ ls
|
ls -l
|
List the current
directory contents with extra details
|
$ ls -l
|
ls
|
Displays files for
the specified path
|
$ ls
|
cd ~ / cd
|
User home
directory
|
$ cd / $ cd ~
|
cd -
|
Previous current
directory
|
$ cd -
|
clear
|
Clear screen
|
$ clear
|
touch
|
Creates an empty
file
|
$ touch abc
|
rm
|
Removes specified
file
|
$ rm abc
|
rm -rf
|
-f force -r
recursive, Removes complete directory with its contents
|
$ rm -rf
|
cp file1 file2
|
Creates a copy of
file1 to file2, if destination is file it creates a duplicate copy, if
destination is directory it moves the file into that directory.
|
$ cp file1 file2
|
cp -r dir1 dir2
|
Creates a
duplicate copy of whole directory
|
$ cp -r dir1 dir2
|
mv file2 file3
|
Renames given file
to new file
|
$ mv file2 file3
|
cat
|
Displays contents
of the file
|
$ cat file1.txt
|
more
|
Displays contents
of the file page by page, for next page {Space} to quit {q}
|
$ more file1.txt
|
head
|
Displays first 10
lines from the file
|
$ head file1.txt
$ head -20
file1.txt (first 20 lines)
|
tail
|
Displays last 10
lines from the file
|
$ tail file1.txt
$ tail -20
file1.txt (last 20 lines)
|
tail -f
|
Displays contents
of the file as it grows, starting with last 10 lines, to quit {ctrl+c}
|
$ tail -f
Kalyan2.err
|
date
|
Displays current
date and time
|
$ date
|
man
|
Display help for
the given command
|
$ man cat
|
command > filename
|
Redirects output
to specified filename
|
$ date >
date.txt
|
command >> filename
|
Appends the
redirected output to existing file
|
$ date >>
date.txt
|
sort file1
|
Sort the contents
of the file
|
$ sort file1
|
| (Pipe)
|
Pipes the output
to other command
|
$ cat file1 | sort
|
ps
|
Displays all
current processes
|
$ ps
|
top
|
Displays all
running processes
|
$ top
|
kill
|
Kills the process
Id
|
$ kill
|
cal
|
Displays current
months calendar
|
$ cal
|
uptime
|
Displays current
uptime
|
$ uptime
|
w
|
Displays who is
online (All the users who are connected to this host)
|
$ w
|
whoami
|
Displays the
current logged in user name
|
$ whoami
|
finger
|
Displays
information about the user
|
$ finger kalyan
|
whereis
|
Displays possible
locations of the given application
|
$ whereis mysql
$ whereis perl
|
which
|
Displays which app
runs
|
$ which mysql
$ which perl
|
uname
|
Prints the system
information
|
$ uname
|
uname -a
|
Prints Kernel
information
|
$ uname -a
|
uname -o
|
Displays operating
system
-o Operating
System
-v Kernel version
-n Node Name
-m Machine
-p Processor
-a All
|
$ uname -o
|
wc
|
Displays number of
newlines, words and bytes in the file
|
$ ls -lrt | wc - l
Displays count for
ls -lrt
|
set
|
Displays the name
and value of each shell vairable
|
$ set
|
$HOME
|
To view value in
any environment variable
|
$ HOME
|
printenv
|
Displays all
environment variable
|
$ printenv
|
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