=====Shell=====

====Variables====

^  Name  ^  Function  ^
|  HISTFILESIZE   |  change the size of your histfile from default 1000 to whatever you put there |
|  HISTTIMEFORMAT=“%F %T  | This add date and time details to History |
|  export LESS=”-X“  | leaves the result of cat on the screen |
|  export EDITOR=/usr/bbin/nano  | change the default editor from vim to nano |

====Commands and Options====

^  Command  ^  Function  ^
|  <nowiki>grep ^[^#]</nowiki> | this will remove the comments of a file you are viewing |
|  !!  | attach the previous command usefull with sudo |
|  sudo -i  | gives interactive shell similar to sudo bash |

===Creating dated backups==
to create a new file and add a time stamp

<code> cp test_file backup_test_file_$(date +%F).txt </code>

This creates a file that looks like backup_testfile_2023-07-25.txt

=-=Tee==-
The tee command tee is used to copy the output of a command and save it to a file

for example

 ls -al | tee listing.txt 
displays the result of ls -al and creates a file listing.txt that contains the same

===getent===
This command is a alternative to just id

here is how to use it
<code>
[u-ansible@dubrhsatserver62 ~]$ getent passwd brindleyp@office.local
brindleyp@office.local:*:1840638513:1840600513:Philip Brindley - RDP:/home/brindleyp@office.local:/bin/bash </code>
as compared to

<code>
[u-ansible@dubrhsatserver62 ~]$ id brindleyp@office.local
uid=1840638513(brindleyp@office.local) gid=1840600513(domain users@office.local) groups=1840600513(domain users@office.local),1840664906(deny_user_autoenroll@office.local),1840634185(rdp_vmwareadmins@office.local),1840633304(hp blade oa administrators@office.local),1840637471(ib_ultrardps@office.local),1840653682(vmware_dmz@office.local),1840641496(sshusers@office.local),1840630206(vmware admins@office.local),1840662085(dmz universal - openshift readonly@office.local),1840662800(openshift readonly@office.local),1840634170(access_vmwaremgmtservers@office.local),1840634171(access_workstations@office.local),1840650567(dmz universal - vmware rdp@office.local)</code>

===exit codes===
after you run a command you can check the exit codes by typing

<code> $?  </code>

| ^  meaning  ^
|  0  | Command completed successfully |
|  1  | Command had an error |
|  2  | OPtion not found  ie searching for text with grep |

===Bash Options===

Use **cd -** to move to last working directory