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Showing posts with label Linux Commands. Show all posts
Showing posts with label Linux Commands. Show all posts

Linux Find Commands with examples.



Linux Find Commands Cheat sheet.

Find Files Using Name in Current Directory.
Lets assume we are currently under our /home directory.
  # find . -name myfile.txt
     /home/myfile.txt


Find Files Using Name and Ignoring Case ( Ignore upper & lower case )


  # find . -iname myfile.txt
     /home/myfile.txt
     /home/MYFILE.txt

Find Files under any specified Directory.


  # find . -iname myfile.txt

     /home/myfile.txt

     /home/MYFILE.txt


Find Files Using Name and Ignoring Case ( Ignore upper & lower case )

      #  find . -iname myfile.txt
    
         /home/myfile.txt
    
         /home/MYFILE.txt


    Find files  based on extention ( .php .txt .csv .sh )


      #  find . -type f -name "*.php"
    
         /home/myfile.php
    
         /home/index.php
    
    
    
     #  find . -type f -name "*.csv"
    
         /home/abc.csv
    
         /home/newfile.csv
    
    
    
     #  find . -type f -name "*.sh"
    
         /home/myscript.sh
    
         /home/new.sh
    
    
    
    
    


    Find Directories 


      #  find . -type d -name  mydirectory
    
    
        /home/mydirectory


    Find files with 777 Permission


      #  find /home   -type f -perm 0777 -print
    
          /home/abc.txt

    Find files without  755 Permission


       #  find /home  -type f ! -perm 755
    
           /home/myfile.txt
    
           /home/MYFILE.txt


    Find  all files Based on User
    We will find all files placed within /home directory having ownership of user jackuna
      #  find /home -user jackuna
    
          /home/myfile.txt


    Find  all files based on specific Group
    We will find all files placed within /home directory having group of user sysadmins
      #  find /home -group sysadmins
    
          /home/admin.sh


    Find  specific file type for a user
    We will find all files with .txt extension for user jackuna under /home directory
      #  find /home -user jackuna -iname "*.txt"
    
         /home/myfile.txt


    Find all empty files ( no content )
    We will find all empty/blank files  under /tmp directory.
       #  find /tmp -type f -empty


    Find all empty directories ( no content )
    We will find all empty/blank directories  under /tmp directory.
       #  find /tmp -type d -empty


    Find all hidden files
    We will find all hidden files under /tmp directory.
       #  find /tmp -type f -name ".*"


    Find  and remove a single file
    We will find file named as  myfile.txt  under /home directory and remove it permanently 
      #  find /home  -type f -name "myfile.txt" -exec rm -f {} \;


    Find  and remove a multi[ple file
    We will find all files with .sh and .mp3 extension under /home and delete it permanently 
      #  find /home -type f -name "*.sh" -exec rm -f {} \;
     
      #  find  /home  -type f -name "*.mp3" -exec rm -f {} \;


    Find files that are older then n number of days 
    Below find command will find all files that are older then 20 days under /tmp directory
      #  find  /tmp -mtime +20 -print
    


    Find files that are accessed then n number of days before
    Below find command will find all files that are accessed  20 days before under /tmp directory
      #  find  /tmp -atime +20 -print


    Find files that are changed within last hour
    Below find command will find all files that are changed within last 60 min under /tmp directory
      #  find /tmp -cmin -60


    Find modified files in last 60 minutes
    Below find command will find all files that are modified within last 60 min under /tmp directory
      #  find /tmp -mmin -60


    Find accessed files in last 60 minutes
    Below find command will find all files that are accessed within last 60 min under /tmp directory
      #  find /tmp -amin -60

    
    
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    BASH Shell Scripting Cheat Sheet : Part 1




    Commonly used UNIX Commands!!

    Cheat sheet to use within your shell scripts


    1.How to display the 10th line of a file?
    head -10 filename | tail -1
    2. How to remove the header from a file?
    sed -i '1 d' filename
    3. How to remove the footer from a file?
    sed -i '$ d' filename
    4. Write a command to find the length of a line in a file?
    The below command can be used to get a line from a file.
    sed –n '<n> p' filename
    We will see how to find the length of 10th line in a file
    sed -n '10 p' filename|wc -c
    5. How to get the nth word of a line in Unix?
    cut –f<n> -d' '
    6. How to reverse a string in unix?
    echo "java" | rev
    7. How to get the last word from a line in Unix file?
    echo "unix is good" | rev | cut -f1 -d' ' | rev
    8. How to replace the n-th line in a file with a new line in Unix?
    sed -i'' '10 d' filename       # d stands for delete
    sed -i'' '10 i new inserted line' filename     # i stands for insert
    9. How to check if the last command was successful in Unix?
    echo $?
    Any integer apart from 0 indicates failure or the last command was unsuccessful
    10. Write command to list all the links from a directory?
    ls -lrt | grep "^l"
    11. How will you find which operating system your system is running on in UNIX?
    uname -a
    12. Create a read-only file in your home directory?
    touch file; chmod 400 file
    13. How do you see command line history in UNIX?
    The 'history' command can be used to get the list of commands that we are executed.
    14. How to display the first 20 lines of a file?
    By default, the head command displays the first 10 lines from a file. If we change the option of head, then we can display as many lines as we want.
    head -20 filename
    An alternative solution is using the sed command
    sed '21,$ d' filename
    The d option here deletes the lines from 21 to the end of the file
    15. Write a command to print the last line of a file?
    The tail command can be used to display the last lines from a file.
    tail -1 filename
    Alternative solutions are:
    sed -n '$ p' filename
    awk 'END{print $0}' filename
    16. How do you rename the files in a directory with _new as suffix?
    ls -lrt|grep '^-'| awk '{print "mv "$9" "$9".new"}' | sh
    17. Write a command to convert a string from lower case to upper case?
    echo "apple" | tr [a-z] [A-Z]
    18. Write a command to convert a string to Initcap.
    echo apple | awk '{print toupper(substr($1,1,1)) tolower(substr($1,2))}'
    19. Write a command to redirect the output of date command to multiple files?
    The tee command writes the output to multiple files and also displays the output on the terminal.
    date | tee -a file1 file2 file3
    20. How do you list the hidden files in current directory?
    ls -a | grep '^\.'
    21. List out some of the Hot Keys available in bash shell?
    Ctrl+l - Clears the Screen.
    Ctrl+r - Does a search in previously given commands in shell.
    Ctrl+u - Clears the typing before the hotkey.
    Ctrl+a - Places cursor at the beginning of the command at shell.
    Ctrl+e - Places cursor at the end of the command at shell.
    Ctrl+d - Kills the shell.
    Ctrl+z - Places the currently running process into background.

    22. How do you make an existing file empty?
    cat /dev/null >  filename
    23. How do you remove the first number on 10th line in file?
    sed '10 s/[0-9][0-9]*//' < filename
    24. What is the difference between join -v and join -a?
    join -v : outputs only matched lines between two files.
    join -a : In addition to the matched lines, this will output unmatched lines also.
    25. How do you display from the 5th character to the end of the line from a file?
    cut -c 5- filename
    26. Display all the files in current directory sorted by size?
    ls -l | grep '^-' | awk '{print $5,$9}' |sort -n|awk '{print $2}'
    27. Write a command to search for the file 'map' in the current directory?
    find -name map -type f
    28. How to display the first 10 characters from each line of a file?
    cut -c -10 filename
    29. Write a command to remove the first number on all lines that start with "@"?
    sed '\,^@, s/[0-9][0-9]*//' < filename
    30. How to print the file names in a directory that has the word "term"?
    grep -l term *
    The '-l' option make the grep command to print only the filename without printing the content of the file. As soon as the grep command finds the pattern in a file, it prints the pattern and stops searching other lines in the file.
    31. How to run awk command specified in a file?
    awk -f filename
    32. How do you display the calendar for the month march in the year 1985?
    The cal command can be used to display the current month calendar. You can pass the month and year as arguments to display the required year, month combination calendar.
    cal 03 1985
    This will display the calendar for the March month and year 1985.
    33. Write a command to find the total number of lines in a file?
    wc -l filename
    Other ways to pring the total number of lines are
    awk 'BEGIN {sum=0} {sum=sum+1} END {print sum}' filename
    awk 'END{print NR}' filename
    34. How to duplicate empty lines in a file?
    sed '/^$/ p' < filename
    35. Explain iostat, vmstat and netstat?
    Iostat: reports on terminal, disk and tape I/O activity.
    Vmstat: reports on virtual memory statistics for processes, disk, tape and CPU activity.
    Netstat: reports on the contents of network data structures.
    36. How do you write the contents of 3 files into a single file?
    cat file1 file2 file3 > file
    37. How to display the fields in a text file in reverse order?
    awk 'BEGIN {ORS=""} { for(i=NF;i>0;i--) print $i," "; print "\n"}' filename

    38. Write a command to find the sum of bytes (size of file) of all files in a directory.
    ls -l | grep '^-'| awk 'BEGIN {sum=0} {sum = sum + $5} END {print sum}'

    39. Write a command to print the lines which end with the word "end"?
    grep 'end$' filename
    The '$' symbol specifies the grep command to search for the pattern at the end of the line.
    40. Write a command to select only those lines containing "july" as a whole word?
    grep -w july filename
    The '-w' option makes the grep command to search for exact whole words. If the specified pattern is found in a string, then it is not considered as a whole word. For example: In the string "mikejulymak", the pattern "july" is found. However "july" is not a whole word in that string.
    41. How to remove the first 10 lines from a file?
    sed '1,10 d' < filename
    42. Write a command to duplicate each line in a file?
    sed 'p' < filename
    43. How to extract the username from 'who am i' comamnd?
    who am i | cut -f1 -d' '
    44. Write a command to list the files in '/usr' directory that start with 'ch' and then display the number of lines in each file?
    wc -l /usr/ch*
    Another way is
    find /usr -name 'ch*' -type f -exec wc -l {} \;
    45. How to remove blank lines in a file ?
    grep -v ‘^$’ filename > new_filename
    46. How to display the processes that were run by your user name ?
    ps -aef | grep <user_name>
    47. Write a command to display all the files recursively with path under current directory?
    find . -depth -print
    48. Display zero byte size files in the current directory?
    find -size 0 -type f
    49. Write a command to display the third and fifth character from each line of a file?
    cut -c 3,5 filename
    50. Write a command to print the fields from 10th to the end of the line. The fields in the line are delimited by a comma?
    cut -d',' -f10- filename


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    How to use Rsync behind proxy



    Usually one needs to export proxies url/ip in order to upload/download content while running behing proxy with shell or any terminal sessions.

    Please keep in mind even exporting  http_proxy and https_proxy , rsync will not work.



    cybeerkeeda@Linux-Maniac:~ export rsync_proxy=xxx.xxx.xx.xx:yyyy

    Do replace rsync_proxy=with_your_proxy_url:port
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    DPKG Cheat Sheet


    DPKG [ dpkg ] is a traditional yet powerful CLI tool for the debian based Linux Distribution.
    It is used to install/manage individual packages.

    Here are some useful dpkg commands which you can use as a cheat code.




    SyntaxDescriptionExample
    dpkg -i {.deb package}Install the packagedpkg -i zip_virtualbox-5.amd64.deb
    dpkg -i {.deb package}Upgrade package if it is installed else install a fresh copy of packagedpkg -i virtualbox-5.amd64.deb
    dpkg -R {Directory-name}Install all packages recursively from directorydpkg -R /tmp/downloads
    dpkg -r {package}Remove/Delete an installed package except configuration filesdpkg -r zip
    dpkg -P {package}Remove/Delete everything including configuration filesdpkg -P apache-perl
    dpkg -lList all installed packages, along with package version and short descriptiondpkg -l
    dokg -l | less
    dpkg -l '*apache*'
    dpkg -l | grep -i 'sudo'
    dpkg -l {package}List individual installed packages, along with package version and short descriptiondpkg -l apache-perl
    dpkg -L {package}Find out files are provided by the installed package i.e. list where files were installeddpkg -L apache-perl
    dpkg -L perl
    dpkg -c {.Deb package}List files provided (or owned) by the package i.e. List all files inside debian .deb package file, very useful to find where files would be installeddpkg -c virtualbox-5.amd64.deb
    dpkg -S {/path/to/file}Find what package owns the file i.e. find out what package does file belongdpkg -S /bin/netstat
    dpkg -S /sbin/ippool
    dpkg -p {package}Display details about package package group, version, maintainer, Architecture, display depends packages, description etcdpkg -p lsof
    dpkg -s {package} | grep StatusFind out if Debian package is installed or not (status)dpkg -s lsof | grep Status
    Read more ...
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