====== Various helpful command line commands ======

===== System =====

Check whether a reboot is required:
  ls /var/run/reboot-required

In a bash script, you can use:
  #!/bin/bash
  if [ -f /var/run/reboot-required ]; then
    echo 'reboot required'
  fi

===== Copy files between servers =====
  - Copy between servers with user privileges<code>$ rsync -avz -e 'ssh -p 22' dir user@x.x.x.x:/path/to/dir/</code>
  - Copy between servers with root privileges<file>$ rsync -avz -e 'ssh -p 22 -i /home/user/.ssh/id_ecdsa' --rsync-path="sudo rsync" dir user@x.x.x.x:/path/to/dir/</file>
    * also enable the user on the target machine to run rsync with root privileges, to do so create file ''/etc/sudoers.d/rsync'' (line 1) with content (line 2)<code>$ sudo visudo /etc/sudoers.d/rsync
user ALL = NOPASSWD:/usr/bin/rsync</code>
  - Copy from cloud<code>$ rsync -avz -e 'ssh -p 22 -i /path/to/identity/file' --info=progress2 user@x.x.x.x:/path/to/dir/ /local/dir/</code>
===== File Management =====

==== Copy all files except some in all sub directories ====
  cd ~/movies
  find . -type d -exec mkdir ~/copied/{} \;
  find . -type f -not -name *.mkv -exec cp {} ~/copied/{} \;

==== Modify file but preserve modified timestamp ====
  cp -p <file> <file-with-timestamp>
  vim <file>
  touch -r <file-with-timestamp> <file>

==== Find all files containing specific text ====
  * Since you have GNU find/xargs, this is a safe way for xargs to read filenames:<code>find . -type f -print0 | xargs -0 grep "some string"</code>
  * If you only want the filenames that have a matching line without showing the matching line:<code>find . -type f -print0 | xargs -0 grep -l "some string"</code>

==== Find all files which were modified within the last month from the current directory ====
  find . -newermt $(date +%Y-%m-%d -d '1 month ago') -type f -print

==== Find all files modified on the 7th of June, 2006 ====
  find . -type f -newermt 2007-06-07 ! -newermt 2007-06-08

==== Find all files accessed on the 29th of september, 2008 ====
  find . -type f -newerat 2008-09-29 ! -newerat 2008-09-30

==== Find files which had their permission changed on the same day ====
  find . -type f -newerct 2008-09-29 ! -newerct 2008-09-30

==== Copy all files excluding hardlinks ====
  rsync -aAXv /origin /dest
  rsync -azAX -H --delete --numeric-ids /path/to/source /path/to/dest

==== Determine size of a folder path ====
  du -hs

==== Change permissions for all files in a directory tree ====
  find -type f -print0 | xargs -0 chmod 644

==== Copy all files ====
  rsync -av <source> <dest>

==== Count all files in a directory (without .files) ====
  ls -1 | wc -l

==== Change the name of all files like "source_1111_22.jpg" to "dest_1111_22.jpg" ====
  rename 's/source_(\d{4}_\d{2})\.jpg$/dest_$1.jpg/' *
If "source" is "sourca" and "sourcb", do the following:
  rename 's/\w{6}_(\d{4}_\d{2})\.jpg$/dest_$1.jpg/' *

==== Delete Directory and Files within recursively ====
  find -type d -name <dir> -exec rm -rf {} \;

==== Refresh display of the last 15 lines of a file every 2 seconds ====
  watch tail -n 15 file.name

==== Zip folder ====
  zip -r myarchive.zip dir1 -x dir1/ignoreDir1/**\* dir1/ignoreDir2/**\*

[[http://www.computerhope.com/unix/rename.htm#03|Linux rename command]]

==== Zip including hidden files ====
  zip -r archive.zip * .[^.]*
[[https://stackoverflow.com/questions/12493206/zip-including-hidden-files|Zip including hidden files]]
===== Disk Management =====

  # iotop
  smartctl -H /dev/sda
  blkid /dev/sda1
  mount -t cifs -o user=luke //192.168.1.104/share /mnt/linky_share
  mdadm --manage /dev/md0 --add /dev/sdb1

Diskspace information:
  df -h

===== VirtualBox =====

VirtualBox
  usermod -a -G groupName userName

Add physical disk:
  VBoxManage internalcommands createrawvmdk -filename /home/bco/.VirtualBox/diskname.vmdk -rawdisk /dev/sda

===== Vim =====

Find each occurrence of 'foo' (in all lines), and replace it with 'bar'.:
  :%s/foo/bar/g

Find each occurrence of 'foo' (in the current line only), and replace it with 'bar':
  :s/foo/bar/g

[[http://vim.wikia.com/wiki/Search_and_replace|Search and Replace]]

==== vi ====

To fix the broken arrow keys in insert mode in vi, change the vi default config as follows:
  $ vi ~/.exrc
  set nocompatible

===== Settings =====

  hostname <newname>
  vim /etc/hostname
  vim /etc/hosts

  vim /usr/share/X11/xorg.conf.d/00-Settings.conf
  Section"ServerFlags"
  Option "BlankTime" "600"
  EndSection

===== Port scan =====

[[https://pentest-tools.com/discovery-probing/tcp-port-scanner-online-nmap|TCP Port Scan with Nmap]]

===== check for root privileges =====

Don't forget to change the root password. If any user has UID 0 besides root, they shouldn't. Bad idea. To check:
  grep 'x:0:' /etc/passwd
Again, you shouldn't do this but to check if the user is a member of the root group:
  grep root /etc/group
To see if anyone can execute commands as root, check sudoers:
  cat /etc/sudoers
To check for SUID bit, which allows programs to be executed with root privileges:
  find / -perm -04000

===== Add a service to the init system =====

Write a script with the LSB tags to be read by the insserv service:
  #!/bin/sh
  ### BEGIN INIT INFO
  # Provides: myservice
  # Required-Start: sshd
  # Required-Stop: sshd
  # Should-Start:
  # Should-Stop:
  # Default-Start: 2 3 4 5
  # Default-Stop: 0 1 6
  # Short-Description: Start myservice
  # Description: Start myservice after sshd is started (example)
  ### END INIT INFO
  myservice -options
  exit 0

Name the script myservice, move it to /etc/init.d/, and run the following command as root:
  # update.rc-d myservice defaults