Linux Commands

1. RPM Version Info:

   • rpm -qa foo

2. Shutdown X11:

   • init 3

3. Reboot the System:

   • init 6

4. Mount a CDROM:

   • mount /dev/cdrom

5. Unmount a CDROM:

   • umount /dev/cdrom

6. List Start Up Scripts:

   • chkconfig --list

7. Turn On Start Up Script:

   • chkconfig service start

8. Turn Off Start Up Script:

   • chkconfig service off

9. Get the kernel version by typing

   • uname -r

10. Format USB Device to Vfat

    •  mkfs.vfat -F 32 /dev/sda1

11. How to create tarball's assuming your directory is called foo:</pre>

    • tar -cvzf foo.tar.gz /dir/foo

12. Add user to Virtual Postfix Database:

    • postmap virtual

13. Enable RAID1 Mirroring ndas:

    • ndasadmin enable -s 1 -o w 2

14. Reload Postfix:

    •  postfix reload

15. Produces Postfix Queue List:

    •  postqueue -p

16. Also Produces Postfix Queue List:

    • mailq

17. Flush Postfix Queues:

    •  postqueue -f

18. Read all postfix config:

    • postconf

19. Remote Desktop for Windows (toggle -f on or off for fullscreen):

    • rdesktop -g 1152x768 -a 24 -b -f mail

20. Unzip bz2 files:

    • bzip2 -cd files.tar.bz2 | tar xvf -

21. Show program install path:

    • which {program}

22. Removes mail from mail queue

    • postsuper -d {queue id}>

23. Displays Hardware info from BIOS (must have installed dmidecode installed)

    • dmidecode

24. To get a Network list of current IP/Hostname's, type the following on the command line:

    • dig axfr hosthame

25. or to sort by IP type:

    • dig axfr hostname |grep IN | egrep A |sort -n  -k 5 -k 7 -t .

26. Type the following to setup rpmq to find true kernel version

    • alias rpmq='rpm --qf '\''%{NAME}-%{VERSION}-%{RELEASE}.%{ARCH}\n'\'' -q'

27. Type the following to determine the kernel version

    • rpmq kernel

28. List all PCI Devices:

    • lspci

29. Reload named:

    • rndc reload

30. Create Database:

    • create database {DATABASE NAME};

31. Create Database Privileges:

    • grant all privileges on {DATABASE NAME}.* to {DATABASE USER}@localhost identified by '{DATABASE PASSWORD}';

32. Set Privileges:

    • flush privileges;

33. Netstat TCP/UDP IP,PORTS

    • netstat -tunlp

34. Create QEMU Disk Images:

    • qemu-img create -f qcow {name}.img 3G

35. Install OS on QEMU Drive Image via CD-ROM

    • qemu -cdrom /dev/cdrom -hda {name}.img -m {memsize} -boot d

36. Install OS on QEMU Drive Image via IMAGE

    • qemu -cdrom {name}.iso -hda {name}.img -m {memsize} -boot d

37. Run QEMU Disk Images with Sound (Blaster16):

    • qemu -hda {name}.img -m {memsize} -soundhw es1370 -localtime

38. Move seamless between host and guest

    • qemu -hda {name}.img -m {memsize} -soundhw es1370 -localtime -usb -usbdevice tablet

39. Resize AVI Files (--export_asr 3 is widescreen and --export_asr 2 is fullscreen)

    • transcode -i INPUT.avi -y ffmpeg,ffmpeg -F mpeg4 -Z 320x,fast --export_asr 2 -o OUTPUT.avi -E 44100,16,2 -b 256

40. Start NetworkManager GUI Applet

    • nm-applet &

41. Set Password for MySQL Root

    • mysqladmin -u root password new-password

42. Remove User account and Home dir

    • userdel -r {username}

43. Mount an ISO image

    • mount -o loop -t iso9660 filename.iso /mnt/iso

44. Create random passwords

    • head /dev/urandom | strings

45. Show partions on a drive

    • sfdisk -l

46. You want to download all the GIFs from an HTTP directory. The command doesn't work since HTTP retrieval does not support globbing. In that case, use:

    • wget -r -l1 --no-parent -A.gif http://host/dir/

47. How to rsync

    • rsync -r -a -v -e "ssh -l {username}" --delete {remote machine}:/dir /dir

48. How to check memory

    •  ps -eo pid,ppid,rss,vsize,pcpu,pmem,cmd -ww --sort=pid

49. How to search and replace recursively within files

    •  find . -type f -exec sed -i s/search/replace/g {} +

50. How to convert Flac to MP3

    • for file in *.flac; do flac -cd "$file" | lame -h - "${file%.flac}.mp3"; done

51. How to check 3ware Hardware RAID status:

    •  tw_cli /c0 show

52. Dirvish Vault first init

    •  dirvish -vault ''vaultname'' --init

53. CIFS mount:

    • mount -o username=username,password=1234,uid=username,gid=groupname,iocharset=utf8,file_mode=0777,dir_mode=0777,noperm //host/disk /mnt/NAS/

54. How to install all development tools:

    • PRE Fedora 18: yum groups install "Development Tools"

    • POST Fedora 18: yum groupinstall development-libs development-tools gnome-software-development

    • apt-get install build-essential

55. How to enable ndadmin slot:

    • ndasadmin enable -s 1 -o w

56. How to install Debian Kernel headers:

    • apt-get install linux-headers-$(uname -r)

57. How to find the largest file/directory human readable from your current directory:

    • du -hsx * | sort -rh | head -10

58. How to list all installed PERL modules:

    • perl -MFile::Find=find -MFile::Spec::Functions -Tlwe  'find { wanted => sub { print canonpath $_ if /\.pm\z/ }, no_chdir => 1 }, @INC'

59. GLOBAL REPLACE in the files (change call to mall in all *.kumac files):

    • awk '{gsub("call", "mall", $0); print > FILENAME}' *.kumac

60. The fastest way to scan all your computers/network subnet for open ports ever:

    • nmap -T5 192.168.1.0/24

61. Convert virtual image files:

    • ovftool --lax input.ovf output.vmx

62. How to extract CPIO file:

    • cpio -id < filename

63. How to remove all symbolic link:

    • find -type l -delete

64. How to find device or partition block size:

    • blockdev --getbsz partition

65. How to convert KVM to VMWARE:

    • qemu-img convert -O vmdk filename.qcow2 filename.vmdk

66. List UUID of all disks:

    • ls /dev/disk/by-uuid -lt

67. Add CDROM to apt:

    • apt-cdrom add

68. Rebuild software RAID:

    • mdadm --assemble --scan

69. Time stamp on history command:

    • HISTTIMEFORMAT="%d/%m/%y %T " && history<pre>

70. Remount read/write:

    • mount -o remount, rw / 

71. Find port number of running application:

    • lsof -Pan -p {PID} -i

72. WAN IP Address from commandline:

    • curl -s ifconfig.co

73. Burn CD/DVD commandline:

    • growisofs -dvd-compat -Z /dev/cdrom=filename.iso

74. Bandwidth Test Commandline:

    • curl -s https://raw.githubusercontent.com/sivel/speedtest-cli/master/speedtest.py | python -

75. Fix E353: Nothing in register "

    • echo set clipboard=unnamed >> ~/.vimrc

76. Find Out Which Process Is Listening Upon a Port:

    • netstat -tulpn

77. Replace all spaces in files within a directory with an underscore:

    • for f in *\ *; do mv "$f" "${f// /_}"; done

78. Disk usage of all directories including hidden:

    • du -sch .[!.]* *

79. Check process by CPU and PID:

    • ps -eo pcpu,pid,user,args | sort -k 1 -r | head -10

80. Create simple HTTP server from present working directory:

    • python -m SimpleHTTPServer

81. Resize img file

    • qemu-img resize test.img 2G

82. a wk vertical to horizontal

    • awk 'ORS=" "' filename

83. Re-read partition table after modifications (SD or USB):

    • partprobe /dev/sdX

84. Find with max depth of 3 directories:

    • find -maxdepth 3

85. Find SCSI/SATA devices

    • lsscsi

86. ecm uncompress multiple files:

    • for i in *; do  ecm-uncompress "$i"; done

87. Force downgrade of package:

    • apt-get install apt=1.4.8 libapt-pkg5.0=1.4.8 apt-utils=1.4.8 libapt-inst2.0:amd64=1.4.8

88. Find package dependencies from repo:

    • debfoster -d package

89. List video drivers used. Search for "configuration":

    • dlshw -c video

90. List all listening network ports:

    • netstat -ntpl

91. Check TCP ports using netcat:

    • nc -w 5 -zv {ipaddress} {port}

92. Check UPD ports using netcat:

    •  nc -u -w 5 -zv {ipaddress} {port}

93. Show Debian/Ubuntu release information:

    • lsb_release  -a

94. Reinstall GRUB on drives after OS is running:

    • dpkg-reconfigure grub-pc

95. Cut example to get full names of users from passwd:

    • cut -d':' -f5 /etc/passwd

96. Deletes any trailing whitespace at the end of each line:

    • :%s/\s\+$//e

97. Check UDP port is open/closed:

    • map -sU -p port ip

98. Unlink all symbolic links in dir:

    • find . -type l -exec unlink {} \;

99. See process in memory:

    • ps wwu -C process

100. See process tree of all processes on system:

     • ps axjf

101. Sort processes memory from highest to lowest:

     • ps -o pid,user,%mem,command axf | sort -b -k3 -r

102. Sort processes CPU from highest to lowest:

     • ps -o pid,user,%cpu,command axf | sort -b -k3 -r

103. Display uncommented lines in a file:

     • cat {filename} | egrep -v "(^#.*|^$)"

104. List all process running on port number

     • lsof -i :8080

105. Show the time and date when Linux was first installed

     • ls -lact --full-time /etc |tail

106. Show SSL Cert information

     • curl --insecure -v https://www.google.com 2>&1 | awk 'BEGIN { cert=0 } /^\* Server certificate:/ { cert=1 } /^\*/ { if (cert) print }'

107. Find largest files by size

     • sudo find / -xdev  -type f -size +100M -exec ls -hla {} \; | sort -nk 5

108. Display SSL Cert expiry date.

     • openssl x509 -enddate -noout -in file.pem

109. Extract and reverse engineer .bin or .img files. Or any other binary:

     • binwalk --dd='.*' file.bin

110. Extract compressed file system:

     • 7z x filename

111. Unzip multiple files with spaces in name:

     • find . -name "*.zip" -exec sh -c 'unzip -n "{}" | head -n 7' \;

112. Remove files past a certain day (Example 5 is five days):

     • find /path/to/files/* -mtime +5 -exec rm {} \;

113. You can use the command below to probe the port 22:

     • sudo lsof -i :22

114. Print history without line numbers or date:

     • fc -l -n 1 | sed 's/^\s*//'

115. Set the "immutable" attribute to make a file non-writable:

     • chattr +i {filename}

116. Set the "unimmutable" attribute to make a file writable:

     • chattr -i {filename}

117. Check webserver a host is using:

     •  wget -q -O- --save-headers domainname.com | grep '^[Ss]erver:' | awk '{print $2}'

118. Look at errors in specific services in systemd:

     • journalctl -xe -u {service name}

119. Convert vertical text to horizontal:

     • tr '\n' ' ' <file.txt

120. Find and sort files by disk space

     • du -sch $(ls -A) 2> /dev/null | sort -rh

121. Find files that uses port 443

     • lsof -i :443

122. Find which directory has the most files:

     • find . -type d | cut -d/ -f 2 | uniq -c