Q. How do you list the files in current directory sorted by size in a UNIX machine?
ls -l | grep ^- | sort -nr
Q. How do you delete blank lines in a file in a UNIX machine ?
cat error.txt | grep -v '^$' >file.txt
Q. How would you display all the files recursively under current directory in a UNIX machine?
find . –depth -print
Q. How would you display disk usage in kilobytes in a UNIX machine?
du -k
Q. Calando of current mont
cal
cal 08 1990
Q. to remove a directory
rm -r tmep
Primary – man(manual) pages.
man shows all information about the command
File Handling commands
• mkdir – make directories
Usage: mkdir [OPTION] DIRECTORY...
eg. mkdir narendra
• ls – list directory contents
Usage: ls [OPTION]... [FILE]...
eg. ls, ls l, ls narendra
• cd – changes directories
Usage: cd [DIRECTORY]
eg. cd narendra
• pwd print name of current working directory
Usage: pwd
• vim – Vi Improved, a programmers text editor
Usage: vim [OPTION] [file]...
eg. vim file1.txt
cp – copy files and directories
Usage: cp [OPTION]... SOURCE DEST
eg. cp sample.txt sample_copy.txt
cp sample_copy.txt target_dir
mv – move (rename) files
Usage: mv [OPTION]... SOURCE DEST
eg. mv source.txt target_dir
mv old.txt new.txt
• rm remove files or directories
Usage: rm [OPTION]... FILE...
eg. rm file1.txt , rm rf some_dir
• find – search for files in a directory hierarchy
Usage: find [OPTION] [path] [pattern]
eg. find file1.txt, find name file1.txt
• history – prints recently used commands
Usage: history
Pattern
A Pattern is an expression that describes a set of strings which is used to give a concise description of a set, without having to list all elements.
eg. ab*cd matches anything that starts with ab and ends with cd etc.
ls *.txt – prints all text files
Text Processing
• cat – concatenate files and print on the standard output
Usage: cat [OPTION] [FILE]...
eg. cat file1.txt file2.txt
cat n file1.txt
• echo – display a line of text
Usage: echo [OPTION] [string] ...
eg. echo I love India
echo $HOME
• grep print lines matching a pattern
Usage: grep [OPTION] PATTERN [FILE]...
eg. grep i apple sample.txt
• wc print the number of newlines, words, and bytes in files
Usage: wc [OPTION]... [FILE]...
eg. wc file1.txt
wc L file1.txt
• sort – sort lines of text files
Usage: sort [OPTION]... [FILE]...
eg. sort file1.txt
sort r file1.txt
Linux File Permissions
• 3 types of file permissions – read, write, execute
• 10 bit format from 'ls l' command
1 2 3 4 5 6 7 8 9 10
file type owner group others
eg. drwxrwr means owner has all three permissions,group has read and write, others have only read permission
• read permission – 4, write – 2, execute 1
eg. rwxrwr = 764
673 = rwrwxwx
System Administration
• chmod – change file access permissions
Usage: chmod [OPTION] [MODE] [FILE]
eg. chmod 744 calculate.sh
• chown – change file owner and group
Usage: chown [OPTION]... OWNER[:[GROUP]] FILE...
eg. chown remo myfile.txt
• su – change user ID or become superuser
Usage: su [OPTION] [LOGIN]
eg. su remo, su
• passwd – update a user’s authentication tokens(s)
Usage: passwd [OPTION]
eg. passwd
• who – show who is logged on
Usage: who [OPTION]
eg. who , who b , who q
• ps – report a snapshot of the current processes
Usage: ps [OPTION]
eg. ps, ps el
• kill – to kill a process(using signal mechanism)
Usage: kill [OPTION] pid
eg. kill 9 2275
Process Management
• tar – to archive a file
Usage: tar [OPTION] DEST SOURCE
eg. tar cvf /home/archive.tar /home/original
tar xvf /home/archive.tar
• zip – package and compress (archive) files
Usage: zip [OPTION] DEST SOURSE
eg. zip original.zip original
• unzip – list, test and extract compressed files in a ZIP archive
Usage: unzip filename
eg. unzip original.zip
Archival
Network
• ssh – SSH client (remote login program)
“ssh is a program for logging into a remote machine and for
executing commands on a remote machine”
Usage: ssh [options] [user]@hostname
eg. ssh X guest@10.105.11.20
• scp – secure copy (remote file copy program)
“scp copies files between hosts on a network”
Usage: scp [options] [[user]@host1:file1] [[user]@host2:file2]
eg. scp file1.txt guest@10.105.11.20:~/Desktop/File Systems
• fdisk – partition manipulator
eg. sudo fdisk l
• mount – mount a file system
Usage: mount t type device dir
eg. mount /dev/sda5 /media/target
• umount – unmount file systems
Usage: umount [OPTIONS] dir | device...
eg. umount /media/target
• du – estimate file space usage
Usage: du [OPTION]... [FILE]...
eg. du
• df – report filesystem disk space usage
Usage: df [OPTION]... [FILE]...
eg. df
• quota – display disk usage and limits
Usage: quota [OPTION]
eg. quota v
Advanced Commands
• reboot – reboot the system
Usage: reboot [OPTION]
eg. reboot
• poweroff – power off the system
Usage: poweroff [OPTION]
eg. poweroff
Editor commands
• kate – KDE Advanced Text Editor
Usage: kate [options][file(s)]
eg. kate file1.txt file2.txt
• vim – Vi Improved, a programmers text editor
Usage: vim [OPTION] [file]...
eg. vi hello.c
• gedit A text Editor. Used to create and edit files.
Usage: gedit [OPTION] [FILE]...
eg. gedit
• bg – make a foreground process to run in background
Usage: type 'ctrl+z' and then 'bg '
• fg – to make background process as foreground process
Usage: fg [jobid]
• jobs – displays the names and ids of background jobs
Usage: jobs
• sed stream editor for filtering and transforming text
Usage: sed [OPTION] [inputfile]...
eg. sed 's/love/hate/g' loveletter.txt
• awk pattern scanning and processing language
eg. awk F: '{ print $1 }' sample_awk.txt
• find search for files in a directory hierarchy
Usage: find [OPTION] [path] [pattern]
eg. find name file1.txt
• locate – find or locate a file
Usage: locate [OPTION]... FILE...
eg. locate file1.txt
In command prompt of widows :
1. Encrypt Files : Cipher /E
2. Change CMD color : color 02 (color help for help)
3. Change prompt text : prompt {Your text} $G (primpt help) 4. Change title of the Window : title myCustumizeName
5. Watch Star Wars in ASCII: telnet towel.blinkenlights.nl 6. Create WiFi Hotspot:
step 1) netsh wlan set hostednetwork mode=allow ssid=HotspotName key=Password
step 2) netsh wlan start hostednetwork
step 3) netsh wlan stop hostednetwork
7. Hide Folders : go to folder and use Attrib +h +s +r folder_name (for hiding)
Attrib -h -s -r folder_name (for visible)
8. Copy Command Output to Clipboard : dir| clip (will copy to clipboard)
9. List all installed programs : wmic product get name
10. Open a CMD window in a directory : type cmd in address bar
11. How to display file-system size in human-readable size units MB, GB df -h