CLECommand Live Environment

Michael Arbet

November 2019

CLE 11/20182

AGENDACommand Line Environment

What, Why, for WhoWhat CLE does, What are its purpose and benefits

Living with CLEInstallation, configuration, usage

The magic insidePriciples, variables, tweaks

CLE 11/20183

What, Why & for Who”Thou shalt have no other shells before bash”

CLE 11/20184

What CLE provides Colorful prompt!

Distinguish commands and outputs

Have important information visible

Create your own style

Alias management

Define and remember aliases

Edit your alias set

Rich history

More information about your work

Endless and easy to search

Live sessionsSeamless login with the same environment without installation

No harm to default settings

Multi-admin environment Open framework

Options to add custom features

Self documented

All in one compact script

CLE 11/20185

Alternatives

1. Your own .bashrc / .zshrc

You know what is there

Need to edit the file, reloginRequired to be added on each new account

2. 'powerline'

Nice, well known solution

Huge complicated python scripts behind

Running daemon! (for just cmdline...)

Requires installation on destination boxes

3. 'sshrc'

Partially solves seamless transfer

Yes this one inspired me!

CLE 11/20186

Who can benefit from CLE

● Administrators, accessing a lot of servers *

● Support engineers creating reproducers

● Developers

● ...anybody using command line daily

*) more users access the same root account with individual settings!

Why this all?

● Install once, use anywhere

● Easy configuration without reload

● Lazy admin's live becomes more comfortable

CLE 11/20187

Living with CLE “Remember the sabbath outage day, to keep it holy”

CLE 11/20188

Start• Main source: http://raw.githubusercontent.com/micharbet/CLE/master/clerc• Easy going: https://git.io/clerc $ wget http://git.io/clerc

$ . clerc$ cle deploy

Exercise #1: download & run

CLE 11/20189

First aid kit

CLE employs TAB autocompletion

CLE is documented, use following ways to learn more:• Quick help (strings inside the script) cle help or cle -h

• Thorough documentation (download) cle doc

You will never walk alone!

CLE 11/201810

Prompting

[0] 12:15 fool stalker.usersys ~ $ _

CLE_P1Username

‘\u’

CLE_P3Working dierctory

‘\w \$’

CLE_P2Shortened hostname

‘^h’

CLE_P0Return code + time

‘^E \A’

Exercise #2: setup prompt colors

cle colorcle color greencle color RgBcle color CgGY

Use predefined scheme or try your own combinations.

CLE 11/201811

Prompting Exercise #3: setup your prompt stringscle time offcle p1 '\u@^h'cle p2 ' $VARIABLE \n'cle p2 '^cM^vVARIABLE'cle p2 'date $(date)'cle p3 '\w:^g \$'

Pro tips: - use TAB completion to get current parts definitions - find more escape sequences using cle doc

Note: distinguish between bash sequences e.g. ‘\u’ and CLE additions introduced with caret sign e.g. ‘^h’

INSERT DESIGNATOR, IF NEEDED12

Live sessions CLE can pass itself over remote login and su*

Exercise #4: Use lssh instead of ssh

CLEWorkstation

srv1[0] fool ws ~ $ lssh root@srv1 (CLE packs itself, transfers through ssh and runs)[0] me-root srv1 ~ # lssh virtual [0] me-root virtual ~ # _ virtual

INSERT DESIGNATOR, IF NEEDED13

Live sessions CLE can pass itself over remote login and su*

Exercise #5: Use lsu, lsudo or lksu

CLEWorkstation

[0] fool ws ~ $ lssh srv1 (CLE packs itself, transfers through ssh and runs)[0] fool srv1 ~ # lksu [0] me-root srv1 ~ # _

root@srv1

fool@srv1

Note: Regular ‘ssh’ and ‘su*’ commands will behave normally, like if CLE does’t exist

CLE 11/201814

CLE in screenUse command lscreen to start CLE session in GNU screen

Features:• Customized configuration• Automatic rejoin detached screens• Easier screen sharing

Exercise #6: work with lscreen• Open more shells <ctrl-A><ctrl-C>• Do something (e.g. ‘ls’)• Switch windows with <ctrl-Left/Right>• Detach screen session <ctrl-A><ctrl-D>• Start over, just type ‘lscreen’

CLE 11/201815

Work with aliases

aaaa tlg='tail -f /var/log/messages

Exercise #7: use command aa

Open new session, new aliases are there!

aaaa -e (you can edit your aliases!)

Define new alias, watch the alias set

CLE 11/201816

Rich history

2018-08-02 11:02:14 mich-8300 15 2 ~/gam-rh gam add group cpq-development-team

2018-08-02 11:02:30 mich-8300 2 0 ~/gam-rh gam create group cpq-development-team

2018-08-02 11:02:37 mich-8300 2 0 ~/gam-rh gam create group clm-development-team

Timestamp session secs rc dir command

h (known bash colored history)

hh (this is the rich history)

hh 15 (recent 15 entries)

hh gam.*group (use regexp)

Basic history usage using hh

Did you know shell's <Ctrl-R> to interactive search through history?

CLE 11/201817

Rich history Advanced searches

hh -d grep (all today’s greps)

hh -shh -tsc (see only successful commands issued in this terminal)

hh -dsc (guess the difference)

hh -f 500 (folder history within recent 500 commands)

Use ‘cle help hh’ to see all rich history options

Exercise #8: • inspect rich history over multiple sessions• Open live session on the same account and watch history

records of other users

CLE 11/201818

The magic inside“Thou shalt not steal unless it is open source”

CLE 11/201819

How CLE works

• Resource file lives in separate folder $HOME/.cle-yourname • Hooked into .${CLE_SH}rc (with command cle deploy)• All in one file, including basic documentation• Defines bash functions – to be executed in context of current shell

process• Seamless live sessions use tar and base64 encoding to pass CLE

files to remote hosts• Self-contained documentation uses '##' double-hash to denote

comments worth to print out using 'cle help'

CLE 11/201820

Internal variables

Issue 'cle env' to inspect all variables

Use ‘cle doc’ and chose file HOWTO.md to read more

Variable PurposeCLE_USER Username from first login on CLE workstation, inherited

over all live sessions. Most important variable used to name cle files

CLE_RC Full path to the resource file itselfCLE_TW Relative path to tweak fileCLE_D Directory with working files (configuration and more)CLE_CF Configuration fileCLE_CLR Color scheme, related command ‘cle color’

CLE_Px (x=0..3) Prompt parts definitions, related commands ‘cle p1..p3’

_Cx Color table, e.g. $_Cr contains escape code for red

CLE 11/201821

FilesFile/folder Purpose

$HOME/.cle-$CLE_USER Here is almost all that CLE needs. Other mentioned files are related to this directory ($CLE_D)

… rc Resource file with the environment itself ($CLE_RC)… cf Configuration file ($CLE_CF)… tw Tweak file ($CLE_TW)… aliases Locally defined aliases$HOME/.history-ALL Rich history file$HOME/.history-$CLE_USER User’s personal history (replaces .bash_history)

Inspect file HOWTO.md using ‘cle doc’ to read more

CLE 11/201822

Tweaks and modules

# this is my CLE tweakecho Welcome $CLE_USER as $USER at $(hostname -f)# Yellow error code_Ce=$_CY

Using ‘cle doc’ inspect following files:TipsAndTweaks.md

Modularity.md

• Try not to edit CLE resource file itself. Instead submit bugs or feature requests on Github

• Place following code into your $HOME/.cle-$CLE_USER/tw:

Make it yours!

Use ‘cle mod’ to enhance functionality, e.g.:cle mod add promptcle prompt triliner

# this is my CLE tweakecho Welcome $CLE_USER as $USER at $(hostname -f)# Yellow error code_Ce=$_CY

CLE 11/201823

Go deeper, have fun• Check how things are coded• Close look at use of variable $CLE_USER – how it is created then

inherited over sessions and how it ensures multi-admin environment.• See comments, esp. Self-documentation• Note, it might be sometimes not easy to read, code is quite dense,

heavily using regular expressions, etc...

Exercise #9: find Easter Egg!● It's there!● Uses function 'cle'

Review the script!

Thank you!“Make love, not core dumps!”

The creator: micharbet@gmail.comThe project: https://github.com/micharbet/CLE