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Linux Command Line - By Ranjan Raja

Ranjan Raja
Ranjan Raja

This document provides a summary of Linux command line cheat sheet covering topics such as: - Simple commands like date, cal, df, free for displaying system information - Navigation commands like cd, ls - Exploring and manipulating files and directories using commands like cp, mv, mkdir, rm - Finding files using locate, find - Process commands like ps, top, kill - Networking commands like ping, traceroute, netstat - Archiving files using gzip, bzip2, tar, zip - User permissions and ownership with chmod, chown, su

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Linux Command Line Cheat Sheet by RANJAN RAJA (Ethical Hacker & Cyber Security Expert) shell prompt # Super User $ normal user simple commands date display current date and time cal display current month calendar df displays disk usages free display memory usage Navigation cd change the current diretcory ls list the directory cd - : change to previous working directory cd ~username : change to home directory Exploring Filesystem file Determine file type less view file contents ls -l diplay in long format -h human readable -a list all files even those hidden, -d directory -F option will append an indictor charactor to the end of listed names -r display result in reverse order -S sort by file Size -t modification time Manipulating Files and Directories cp copy the files mv move the files from one folder to other mkdir creates a directory rm remove files and directories Manipulating Files and Directories (cont) ln create Hard and symbolic link * any character ? any single character [ character] any character that is a member of character [ ! character] any character that is not a member of character [[:class:]] any character that is a member of class command Options : cp, mv i interactive same in mv a copy files and directories of all attributes, ownership and permission - r recursively copies directories and contents same in mv u copy the files that don't exists same in mv v verbose, informative message same in mv Command Substitution echo $(ls) ls -l $(which cp) new method ls -l which cp back tick, old method Process ps reports snap shot of current process top diskplays task jobs list active jobs bg place a job in the background fg place a job in the foreground kill send a signal to process killall kill process by name Process commands ps aux BSD style ouptut fg %1 jobs kill -1 13456 kill process id 13456 SIGNALS: HUP, INT, KILL, TERM,C ONT,STOP,QUIT, SEGV, TSTP. WINCH Find command cmin match attributes/files/dir modified, n minutes cnewer match file/dir whose content or attribute were last modified n*24 ago ctime n match file or direct whose content or attribute were modified n*24 hrs ago empty match empty files and direct ories group name match files or direc belonging to group name iname pattern like the iname test but case insensitive inum n match files with inode number mmin n match files or dir whose content were modified n minutes ago mtime n match files or dir whose content were modified n*24 hours ago name pattern match files and dir with specified wildcard pattern nouser match files and dir that don't belong to valid user nogroup match files and dir that don't belong to valid group Published 27th June, 2022. Page 1 of 6. By - Educonf Technologies Pvt. Ltd. www.educonftech.com www.ethicalhackingpatna.com EDUCONF TECHNOLOGIES
Find command (cont) perm mode match files and directories set to specified mode samefile name matches files that share the same inode number as file name size n match file size of n type c match file type of c user match file and directories belong to user find %test %action %options find ~ find ~ | wc -l find ~ -type d | wc -l ---------------------------- b block c character special device d directory f regular file l symbolic link Find Logical Operator and or not find ~ ( -type f -not -perm 0600 ) -or ( - type d -not -perm -700 ) find -actions delete ls print quite find ~ -type f -name '*.BAR] -print find ~ -type f -and -name '*.BAR -and -print Userdefined actions -exec comman{} find ~ -type f -name 'foo*' -exec ls -l '{}' + find ~ -type f -name 'foo*' -exec ls -l '{}' ';' Find Options - scope depth to process a directory files before the dir itself maxdepth max num of level that find will descend into a directory when performing test and action mindepth min num of level that find will descend into a directory when performing test and action mount direct find not to traverse directories that mounter on other filesystem Tricks clear clears the screen history stores the history script file capture all command execution in a file history: CTRL + {R, P } !!number : command history number !! : last command !?string : history containing last string !string : history containing last string export HISTCONTROL=ignoredups export HISTSIZE=10000 Working With Commands type Indicate how command name is interpreted which display which executable program will be executed man Display manual page apropos Display appropriate command info Display command Info entry whatis Display brief description of command Working With Commands (cont) alias create an alias for command man page options 1 User commands 2 Programming interface for system calls 3 Programming interface for C Library 4 Special files such devies nodes and drivers 5 file formats 6 Games and screen savers 7 misc 8 system administrator commands Redirection cat concatenates files sort sort the file uniq report or omit repeated lines grep print lines matching pattern head prints first few lines of file tail prints las few lines of file tee reads stdin and send output to stdout and file wc count number of line, words, and bytes Redirection Operator ls -l /usr/bin >file default stdout to file ls -l /usr/bin 2>file redirects stderr to file ls -l /usr/bin > ls- output 2>&1 redirects stderr & stdout to file ls -l /usr/bin &> ls- output redirects stderr & stdout to file
Redirection Operator (cont) ls -l /usr/bin 2> /dev/null /dev/null bitbucket Pipelines | pipelines ls -l /usr/bin/ | tee out | sort tee reads stdin and writes to files and stdout view the world as SHELL viewed echo * expands all files in the path echo D* expands all files with starting D $((expression)) Arithematic expression echo $(($((5*2))3)) 75 ls -l which cp backtick instead of expression Braces Expansion echo Front-{A, B,C}-Back Front-A-Back, Front-B-Back, Front-C-Back echo {Z..A} Z Y X W V U .....A mkdir {2009..20 11}-0{1..9} {2009..2011}-{1 0..12} creates a directory for 12 months in 2009 to 2011 Environment printenv Print part of all of the enviro nment set set shell options export export environment to subseq uently executed programs Environment (cont) alias create an alias for command Login & Non Login Shell Login Shells : /etc/profile : global configuration ~/.bash_profile : personal startup efile ~/.bash_login. : if ~/.bash_profile is not found, bash attempts to read this script ~/.profile : if neither ~/.bash_profile & ~/.bash_login bash reads this file Non Login shells : /etc/bash.bashrc : Global configuration ~/.bashrc : User configuration Quoting echo This is a test This is a test; space is stripped echo "This is a test" This is a test echo '$(echo foo) $((2+2))' $(echo foo) $((2+2)) echo the total is $500.00 $5 is undefined variable so it supress the value, output will be like the total is 00.00 " " : all special character looses its meaning, exception ($, , `) ' ' : all special character looses its meaning, and no exceptions Searching For Files locate find files by name find search for files in a dir xargs build and exec cmd lines from stdin touch change the file times Searching For Files (cont) stat display file or filesystem status Networking Ping Send ICMP packets traceroute Print route packets to a network netstat print network connection, routing table, interface stats ftp/lftp Internet file transfer program wget Non Interactive network downloader ssh OpenSSH SSH Client (remote login program) scp secure copy sftp Secure File transfer program OpenSSH package includes two programs that can make use of an SSH encrypted tunnel to copy file across the network. a) scp b) sftp SFTP doesn't require ftp server to connect, it needs only SSH running in machines, any machine that has ssh running, we can able to transfer files to server Archiving and Backup gzip Compress or expand files bzip2 A block sorting file compressor tap tape archving utility zip Package and compress files rsync remote file and dir synchronization unzip Unzip the gzip files compression algorithm: Lossy and Lossless
Hacks Examples: ssh remote-sys 'tar cf - Document' | tar xf - find playground -name 'file-A' | tar czf playground.tgz -T - find playground -name 'file-A' | tar cjf playgr ound.tgz -T - rsync -av --delete --rsh=ssh /etc /home /usr/local remote-sys:/backup - or Hyphen is the stdin and stdout Text processing examples cat -A $FILE To find any CTRL character introduced sort file1.txt file2.txt file3.txt > final_sor ted_list.txt sort all files once ls - l | sort -nr -k 5 key field 5th column sort --key=1,1 -- key=2n distor.txt key field 1,1 sort and second column sort by numeric sort foo.txt | uniq -c to find repetition cut -f 3 distro.txt cut column 3 cut -c 7-10 cut character 7 - 10 cut -d ':' -f 1 /etc/p assword delimiter : sort -k 3.7nbr -k 3.1nbr -k 3.4nbr distro.txt 3 rd field 7 the character, 3rd field 1 character paste file1.txt file2.txt > newfil e.txt merge two files join file1.txt file2.txt join on common two fields Text processing cat concatenate files and print stdout sort sort lines of text files uniq report or omite repeated lines cut remove section from each line of files paste merge lines of files join join lines of two files on a common field comm compare two sorted files line by line diff compare files patch apply a diff file to original tr translate sed stream editor aspel interactive spell checker Permissions id display user identity chmod change's file mode umask set the default file permission su Run a shell as another user sudo Execute command as another user chown changes file's owner chgrp change file groups owner passwd change a user password Read,Write, Execute - | rwx | rw- | r- - type | owner | group | world type - regular file d directory l symbolic link c character device b block device File Mode [Octal] 000 --- 001 --x 010 -w- 011 -wx 100 r-- 101 r-x 110 rw- 111 rwx chmod 0600 file [ rw- is set for owner ] Mode symbolic notation ugo user, group, others u+x giving exeute permission for user u=rw,o=x giveing user read write and others execute perm chmod u=rw,o=x file.txt Packaging Ssystem Debian Style (.dep) Debain, ubuntu, xandros, Linspire RedHat style(.rpm) Fedora, CentOS, Redhat Enterprise, OpenSUSE, Mandriva, PCLinuxOS Install from Repo debian apt-get install package_name redhat yum install package_name Operation on Package File Debian : dpkg --install packagefile apt-get remove package_name apt-get update dpkg --list dpkg --status package_name ch
Operation on Package File (cont) apt-cache show package_name (info about package) dpkg --search file_name (finding which package installed) Redhat : rpm -i packagefile yum erase package_name yum update rpm -u packagefile rpm -qa. (list) rpm -q package_name (check package installed) yum info package_name rpm -qf file_name (finding which package installed) storage media mount mount a filesystem ummount unmount a file system fdisk partition table manipulator fsck check and repair filesystem fdformat format floppy disk mkfs create a file system dd write a block oriented data directly to a device geniso image create an ISO 9660 image file wodim Write data to optical storage device md5sum calculate md5sum dd if=/dev/cdrom of=ubuntu.iso (create image file) fsck /dev/sdb1 (check file system) mkfs -t ext3 /dev/sdb1 (create ext3 file system) unmount /dev/sdb1 (unmount the file system, before changing the partition table) fdisk /dev/sdb (create a partition table ) POSIX charcter class character class alnum, word , alpha blank, cntrl, digit, graph,lowe, punct, print, space, upper, xdigit format: [ :alnum: ] echo $LANG export LANG=POSIX grep Options i ignore case v invert match c print number of matches l print the name of each file that contain matches L print only the names of files that don't match n print match line with the number h for multiple output supress the output of filename grep [options] regex [file....] metacharacters : ^ $ . [ ] {} - ? * + ( ) | grep examples grep -h '.zip' file.list . is any character grep -h '^zip' file.list starts with zip grep -h 'zip$' file.list ends with zip grep -h '^zip$' file.list containing only zip grep -h '[^bz]zip' file.list not containing b and z grep -h '^[A-Za-z0- 9]' file.list file containing any valid names grep Quantifiers ? match element zero or one time * match an element zero or more times + Match an element one or more times {} match an element specfic number of times It always match the preceding element {n} match the preceding element occurs n times {n,m} match the preceding element occurs at least n times, but no more than m times {n,} match the preceding element if it occurs n or more times {,m} match the preceding element if it occurs no more than m times grep hacks grep -E '^([0-9]{3}).[0-9]{3}.[0-9]{3}$' phone.txt locate --regex 'bin/(bz|gz|zip)' for i in {1..10}; do echo "(${RANDOM:0:3})- ${RANDOM:0:3}-${RANDOM:0:3}"; done >>phone.txt Text Processing Hacks diff -c context format diff -u unified format diff -Naur oldfile newfile > diff_file write the diff to diff file patch < diff_file applied to oldfile directly. echo "secret text" | tr a- zA-Z n-za-mN-ZA-M frperg grkg | ROT13 Encoding
Text Processing Hacks (cont) echo "frperg grkg" | tr a- zA-Z n-za-mN-ZA-M secret text | ROT13 Decoding -, +, ! : deleted, added, line changes. $diff -Naur file1.txt file2.txt > diff_file.txt $patch < diff_file.txt patching file file1.txt rotate by 13 places (ROT13)

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Linux Command Line - By Ranjan Raja

  • 1. Linux Command Line Cheat Sheet by RANJAN RAJA (Ethical Hacker & Cyber Security Expert) shell prompt # Super User $ normal user simple commands date display current date and time cal display current month calendar df displays disk usages free display memory usage Navigation cd change the current diretcory ls list the directory cd - : change to previous working directory cd ~username : change to home directory Exploring Filesystem file Determine file type less view file contents ls -l diplay in long format -h human readable -a list all files even those hidden, -d directory -F option will append an indictor charactor to the end of listed names -r display result in reverse order -S sort by file Size -t modification time Manipulating Files and Directories cp copy the files mv move the files from one folder to other mkdir creates a directory rm remove files and directories Manipulating Files and Directories (cont) ln create Hard and symbolic link * any character ? any single character [ character] any character that is a member of character [ ! character] any character that is not a member of character [[:class:]] any character that is a member of class command Options : cp, mv i interactive same in mv a copy files and directories of all attributes, ownership and permission - r recursively copies directories and contents same in mv u copy the files that don't exists same in mv v verbose, informative message same in mv Command Substitution echo $(ls) ls -l $(which cp) new method ls -l which cp back tick, old method Process ps reports snap shot of current process top diskplays task jobs list active jobs bg place a job in the background fg place a job in the foreground kill send a signal to process killall kill process by name Process commands ps aux BSD style ouptut fg %1 jobs kill -1 13456 kill process id 13456 SIGNALS: HUP, INT, KILL, TERM,C ONT,STOP,QUIT, SEGV, TSTP. WINCH Find command cmin match attributes/files/dir modified, n minutes cnewer match file/dir whose content or attribute were last modified n*24 ago ctime n match file or direct whose content or attribute were modified n*24 hrs ago empty match empty files and direct ories group name match files or direc belonging to group name iname pattern like the iname test but case insensitive inum n match files with inode number mmin n match files or dir whose content were modified n minutes ago mtime n match files or dir whose content were modified n*24 hours ago name pattern match files and dir with specified wildcard pattern nouser match files and dir that don't belong to valid user nogroup match files and dir that don't belong to valid group Published 27th June, 2022. Page 1 of 6. By - Educonf Technologies Pvt. Ltd. www.educonftech.com www.ethicalhackingpatna.com EDUCONF TECHNOLOGIES
  • 2. Find command (cont) perm mode match files and directories set to specified mode samefile name matches files that share the same inode number as file name size n match file size of n type c match file type of c user match file and directories belong to user find %test %action %options find ~ find ~ | wc -l find ~ -type d | wc -l ---------------------------- b block c character special device d directory f regular file l symbolic link Find Logical Operator and or not find ~ ( -type f -not -perm 0600 ) -or ( - type d -not -perm -700 ) find -actions delete ls print quite find ~ -type f -name '*.BAR] -print find ~ -type f -and -name '*.BAR -and -print Userdefined actions -exec comman{} find ~ -type f -name 'foo*' -exec ls -l '{}' + find ~ -type f -name 'foo*' -exec ls -l '{}' ';' Find Options - scope depth to process a directory files before the dir itself maxdepth max num of level that find will descend into a directory when performing test and action mindepth min num of level that find will descend into a directory when performing test and action mount direct find not to traverse directories that mounter on other filesystem Tricks clear clears the screen history stores the history script file capture all command execution in a file history: CTRL + {R, P } !!number : command history number !! : last command !?string : history containing last string !string : history containing last string export HISTCONTROL=ignoredups export HISTSIZE=10000 Working With Commands type Indicate how command name is interpreted which display which executable program will be executed man Display manual page apropos Display appropriate command info Display command Info entry whatis Display brief description of command Working With Commands (cont) alias create an alias for command man page options 1 User commands 2 Programming interface for system calls 3 Programming interface for C Library 4 Special files such devies nodes and drivers 5 file formats 6 Games and screen savers 7 misc 8 system administrator commands Redirection cat concatenates files sort sort the file uniq report or omit repeated lines grep print lines matching pattern head prints first few lines of file tail prints las few lines of file tee reads stdin and send output to stdout and file wc count number of line, words, and bytes Redirection Operator ls -l /usr/bin >file default stdout to file ls -l /usr/bin 2>file redirects stderr to file ls -l /usr/bin > ls- output 2>&1 redirects stderr & stdout to file ls -l /usr/bin &> ls- output redirects stderr & stdout to file
  • 3. Redirection Operator (cont) ls -l /usr/bin 2> /dev/null /dev/null bitbucket Pipelines | pipelines ls -l /usr/bin/ | tee out | sort tee reads stdin and writes to files and stdout view the world as SHELL viewed echo * expands all files in the path echo D* expands all files with starting D $((expression)) Arithematic expression echo $(($((5*2))3)) 75 ls -l which cp backtick instead of expression Braces Expansion echo Front-{A, B,C}-Back Front-A-Back, Front-B-Back, Front-C-Back echo {Z..A} Z Y X W V U .....A mkdir {2009..20 11}-0{1..9} {2009..2011}-{1 0..12} creates a directory for 12 months in 2009 to 2011 Environment printenv Print part of all of the enviro nment set set shell options export export environment to subseq uently executed programs Environment (cont) alias create an alias for command Login & Non Login Shell Login Shells : /etc/profile : global configuration ~/.bash_profile : personal startup efile ~/.bash_login. : if ~/.bash_profile is not found, bash attempts to read this script ~/.profile : if neither ~/.bash_profile & ~/.bash_login bash reads this file Non Login shells : /etc/bash.bashrc : Global configuration ~/.bashrc : User configuration Quoting echo This is a test This is a test; space is stripped echo "This is a test" This is a test echo '$(echo foo) $((2+2))' $(echo foo) $((2+2)) echo the total is $500.00 $5 is undefined variable so it supress the value, output will be like the total is 00.00 " " : all special character looses its meaning, exception ($, , `) ' ' : all special character looses its meaning, and no exceptions Searching For Files locate find files by name find search for files in a dir xargs build and exec cmd lines from stdin touch change the file times Searching For Files (cont) stat display file or filesystem status Networking Ping Send ICMP packets traceroute Print route packets to a network netstat print network connection, routing table, interface stats ftp/lftp Internet file transfer program wget Non Interactive network downloader ssh OpenSSH SSH Client (remote login program) scp secure copy sftp Secure File transfer program OpenSSH package includes two programs that can make use of an SSH encrypted tunnel to copy file across the network. a) scp b) sftp SFTP doesn't require ftp server to connect, it needs only SSH running in machines, any machine that has ssh running, we can able to transfer files to server Archiving and Backup gzip Compress or expand files bzip2 A block sorting file compressor tap tape archving utility zip Package and compress files rsync remote file and dir synchronization unzip Unzip the gzip files compression algorithm: Lossy and Lossless
  • 4. Hacks Examples: ssh remote-sys 'tar cf - Document' | tar xf - find playground -name 'file-A' | tar czf playground.tgz -T - find playground -name 'file-A' | tar cjf playgr ound.tgz -T - rsync -av --delete --rsh=ssh /etc /home /usr/local remote-sys:/backup - or Hyphen is the stdin and stdout Text processing examples cat -A $FILE To find any CTRL character introduced sort file1.txt file2.txt file3.txt > final_sor ted_list.txt sort all files once ls - l | sort -nr -k 5 key field 5th column sort --key=1,1 -- key=2n distor.txt key field 1,1 sort and second column sort by numeric sort foo.txt | uniq -c to find repetition cut -f 3 distro.txt cut column 3 cut -c 7-10 cut character 7 - 10 cut -d ':' -f 1 /etc/p assword delimiter : sort -k 3.7nbr -k 3.1nbr -k 3.4nbr distro.txt 3 rd field 7 the character, 3rd field 1 character paste file1.txt file2.txt > newfil e.txt merge two files join file1.txt file2.txt join on common two fields Text processing cat concatenate files and print stdout sort sort lines of text files uniq report or omite repeated lines cut remove section from each line of files paste merge lines of files join join lines of two files on a common field comm compare two sorted files line by line diff compare files patch apply a diff file to original tr translate sed stream editor aspel interactive spell checker Permissions id display user identity chmod change's file mode umask set the default file permission su Run a shell as another user sudo Execute command as another user chown changes file's owner chgrp change file groups owner passwd change a user password Read,Write, Execute - | rwx | rw- | r- - type | owner | group | world type - regular file d directory l symbolic link c character device b block device File Mode [Octal] 000 --- 001 --x 010 -w- 011 -wx 100 r-- 101 r-x 110 rw- 111 rwx chmod 0600 file [ rw- is set for owner ] Mode symbolic notation ugo user, group, others u+x giving exeute permission for user u=rw,o=x giveing user read write and others execute perm chmod u=rw,o=x file.txt Packaging Ssystem Debian Style (.dep) Debain, ubuntu, xandros, Linspire RedHat style(.rpm) Fedora, CentOS, Redhat Enterprise, OpenSUSE, Mandriva, PCLinuxOS Install from Repo debian apt-get install package_name redhat yum install package_name Operation on Package File Debian : dpkg --install packagefile apt-get remove package_name apt-get update dpkg --list dpkg --status package_name ch
  • 5. Operation on Package File (cont) apt-cache show package_name (info about package) dpkg --search file_name (finding which package installed) Redhat : rpm -i packagefile yum erase package_name yum update rpm -u packagefile rpm -qa. (list) rpm -q package_name (check package installed) yum info package_name rpm -qf file_name (finding which package installed) storage media mount mount a filesystem ummount unmount a file system fdisk partition table manipulator fsck check and repair filesystem fdformat format floppy disk mkfs create a file system dd write a block oriented data directly to a device geniso image create an ISO 9660 image file wodim Write data to optical storage device md5sum calculate md5sum dd if=/dev/cdrom of=ubuntu.iso (create image file) fsck /dev/sdb1 (check file system) mkfs -t ext3 /dev/sdb1 (create ext3 file system) unmount /dev/sdb1 (unmount the file system, before changing the partition table) fdisk /dev/sdb (create a partition table ) POSIX charcter class character class alnum, word , alpha blank, cntrl, digit, graph,lowe, punct, print, space, upper, xdigit format: [ :alnum: ] echo $LANG export LANG=POSIX grep Options i ignore case v invert match c print number of matches l print the name of each file that contain matches L print only the names of files that don't match n print match line with the number h for multiple output supress the output of filename grep [options] regex [file....] metacharacters : ^ $ . [ ] {} - ? * + ( ) | grep examples grep -h '.zip' file.list . is any character grep -h '^zip' file.list starts with zip grep -h 'zip$' file.list ends with zip grep -h '^zip$' file.list containing only zip grep -h '[^bz]zip' file.list not containing b and z grep -h '^[A-Za-z0- 9]' file.list file containing any valid names grep Quantifiers ? match element zero or one time * match an element zero or more times + Match an element one or more times {} match an element specfic number of times It always match the preceding element {n} match the preceding element occurs n times {n,m} match the preceding element occurs at least n times, but no more than m times {n,} match the preceding element if it occurs n or more times {,m} match the preceding element if it occurs no more than m times grep hacks grep -E '^([0-9]{3}).[0-9]{3}.[0-9]{3}$' phone.txt locate --regex 'bin/(bz|gz|zip)' for i in {1..10}; do echo "(${RANDOM:0:3})- ${RANDOM:0:3}-${RANDOM:0:3}"; done >>phone.txt Text Processing Hacks diff -c context format diff -u unified format diff -Naur oldfile newfile > diff_file write the diff to diff file patch < diff_file applied to oldfile directly. echo "secret text" | tr a- zA-Z n-za-mN-ZA-M frperg grkg | ROT13 Encoding
  • 6. Text Processing Hacks (cont) echo "frperg grkg" | tr a- zA-Z n-za-mN-ZA-M secret text | ROT13 Decoding -, +, ! : deleted, added, line changes. $diff -Naur file1.txt file2.txt > diff_file.txt $patch < diff_file.txt patching file file1.txt rotate by 13 places (ROT13)
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