Most used UNIX commands

ls Commands (list) :

•  ls : list the files
•  ls -a : list the hidden files
•  ls -al : list the hidden files with long formatting
•  ls -R : list the recursive directory tree
•  ls -t : list the files with time
•  ls -s : list the file size
•  ls -i : list the file size with index number
•  ls -ls : size with long format
•  ls -X : extension name
•  ls -S : sort by file size

cd Command (change directory) :

•  cd / : move to root directory
•  cd ~ : move to home directory
•  cd .. : go back one step
•  cd ~/directory : jump from one directory to another directly
•  cd /root/directory : absolute path of directory
•  cd directory : Relative path of directory
•  cd dir1/dir2 : moving directly to dir2 inside the dir1.
•  cd : move directly to the home directory
•  cd ~prakash : takes to other user login

pwd Commands (print working directory) :

•  pwd : print the working directory
•  /bin/pwd –version : print the version of pwd command
•  type -a pwd : print all the locations containing executable named pwd
•  PS1=’pwd>’ : change current working directory to anything
•  nano pwd.sh : create a shell script
•  chmod pwd.sh : give executive permission

mkdir commands (make directory):

•  mkdir dirname : create a new directory
•  mkdir -m a=rwx dirname : create a new directory and set permissions
•  mkdir -p /root/mine/a/b : create a specified intermediate directories to verify this “du mine”
•  mkdir –version : shows the version of the installed mkdir
•  mkdir -m 777 mine : create a new directory and set the permission as per numbers

rm commands(remove) :

•  rm file1 : delete the file1
•  rm -r dir1 : delete the dir1
•  rm -f file1 : delete the file1
•  rm -rf dir1 : force remove the dir1
•  rm file1 file2 file3 : delete the 3 files simultaneously
•  rmdir dir1 dir2 dir3 : delete the 3 directories simultaneously
•  rm -ri dir1 : delete file and sub directories interactively(-ri option in rm cmd)
•  rm -f *.txt : delete all the .txt file

cp commands (copy) :

•  cp file1 file2 : copy file1 to file2
•  cp -r dir1 dir2 : copy dir1 to dir2
•  cp *.txt dir1 : copy and move all the .txt files to dir1
•  cp -f file.txt dir1 : force file copy to dir1
•  cp -i file.txt dir1 : interactive prompt before file overwrite
•  cp -u * dirname : copy all the files to the directory

mv command (move) :

•  mv file1 file2 : rename the file1 to file2
•  mv file1 dir1 : move the file1 to the destination directory
•  mv file1 ../ : move the file1 to the root directory
•  mv *.txt dir 1 : move the all .txt files to dir1
•  mv dir1/* . : move all files in the subdirectory dir1 to current directory
•  mv dir1 dir2 : move the dir1 to dir2

ln Commands (link) :

•  ln -s file1 dirname : create a symbolic link “link” to file
•  ln -s file1 file2 : create a symbolic link to a files
•  ln -s -b file1.txt file2.txt : file1.txt is renamed to file2.txt , file2.txt symlink is created

touch command :

•  touch file1 : create a new file1
•  touch file1 file2 file3 : create multiple files simultaneously
•  touch -a test.txt : change file access and modification
•  touch -c test.txt : avoid creating new file
•  touch -m test.txt : change file modification time
•  touch {A..Z}   : create file with names A to Z
•  touch {1..20 : Create files with name 1 to 10
•  touch {A..N}.txt : create file with extension
•  touch {1..10}{1..1000} : create 10k files
•  touch -c -t 12101730 test.txt : set the access and modification times
•  touch -r file  leena : use time stamp of another file
•  touch -d ’14:24′ abc.txt ” : specify datetime as a string

cat command (concatenate) :

•  ct /etc/shells : display all the shell commands
•  cat /etc/passwd : display contents of file
•  cat file file1 : view contents of multiple files
•  cat >test1 : create a file with cat command
•  cat file.txt | more : use cat command with more option
•  cat file.txt | less : use cat command with less option
•  cat -n file.txt : display numbers in file
•  cat -e file : display $ at the EOF
•  cat file1; file2 file3; : diplay multiple file contents simultaneously more command :

more command :

•  more +3 file1.txt : display the contents of file1.txt , beginning at line 3
•  more +/”hope” file : display the content of the file ,  beginning at the first line containing the string “hope”.
•  ls | more : List the contents of the current directory with ls, using more to display the list one screen at a time.

head commands :

•  head test : print the first 10 lines from the files
•  head -n2 test :  print the first N lines from the file
•  head -n -2 test : Skip the last N lines from the file
•  head -c 5 test : print the first N bytes from the file
•  head -c -7 test : to skip printing last N bytes
•  head -n 10 test | tail -5 : Print the lines b/w the line numbers M and N
•  head -n 2 /etc/passwd : print the first 2 lines of a file
•  head -n -27 /etc/passwd :  it printed all the lines starting after the line 27

tail commands :

•  tail test : print the last 10 lines of the file
•  tail test -n 100 : Outputs the last 100 lines of the file myfile.txt
•  tail -n 2 /etc/passwd : print the last 2 lines of a file
•  tail -n-2 test : Print the last N lines from the file
•  tail -f test :  output the contents of file as it grows, starting with the last 10 lines Process Management .
•  tail -c-7 test : print the last N bytes
•  tail -n10 test | head -5 : Print the lines b/w the line numbers M and N
•  tail -n -27 /etc/passwd :  it printed all the lines starting before the line 27