KET/KTL 2020 Introduction to the Shell Command Language and Standard Tools Overview with Examples Jan Bělohoubek Aims of this Lecture 3 Command Line Interface – CLI 1 Aims of this Lecture Motivation (Anketa) 4 (Our) BASH Reference 2 Unix Operating Systems 1/26 Aims of this Lecture Motivation (Anketa) provide an overview on "classical" engineering SW tools no more "What is this?" ! hands on . but gently our time is limited speed-up the learning curve as you will face it Area/Tool GNU/Linux CLI Scripting VCS Make SSH Embedded SW maybe probably of course of course of course maybe Application SW maybe probably of course of course of course probably Digital Design probably probably of course of course probably probably PCB Design maybe maybe probably of course maybe maybe Mechanical maybe maybe maybe probably rather not rather not Design Research+1 of course of course of course of course of course of course 1Simulations, Supercomputing, Networking, Control, AI . 1/26 Unix Operating Systems Linux Distributions Popular in Industry 1 Aims of this Lecture (EDA) Linux Distributions 2 Unix Operating Systems Popular for Home Use Brief History Unix/Linux 3 Command Line Interface – Surprising/New Features CLI How To Start . for Windows Users 4 (Our) BASH Reference 2/26 Unix Operating Systems Brief History Image source: https://en.wikipedia.org/wiki/History_of_Unix 1969 Unnamed PDP-7 operating system 1969 Open source 1971 to 1973 Unix 1971 to 1973 Version 1 to 4 Mixed/shared source 1974 to 1975 Unix 1974 to 1975 Closed source Version 5 to 6 PWB/Unix 1978 1978 BSD 1.0 to 2.0 Unix 1979 Version 7 1979 Unix/32V 1980 1980 BSD 3.0 to 4.1 Xenix 1981 System III 1981 1.0 to 2.3 1982 1982 Xenix 3.0 1983 BSD 4.2 SunOS 1983 1 to 1.1 System V R1 to R2 1984 SCO Xenix 1984 Unix 1985 Version 8 SCO Xenix 1985 AIX V/286 System V 1986 Unix-like systems BSD 4.3 1.0 R3 HP-UX 1986 SunOS SCO Xenix 1.0 to 1.2 Unix 1.2 to 3.0 1987 V/386 1987 9 and 10 HP-UX 1988 (last versions BSD 4.3 System V 1988 2.0 to 3.0 from Tahoe R4 1989 Bell Labs) SCO Xenix 1989 BSD Net/1 V/386 BSD 4.3 1990 Reno 1990 1991 BSD Net/2 1991 Linux 0.0.1 SunOS 4 Minix 386BSD 1.x NexTSTEP/ 1992 OPENSTEP HP-UX 1992 1.0 to 4.0 NetBSD 6 to 11 0.8 to 1.0 Linux BSD 1993 SCO UNIX UnixWare 1993 0.95 to 1.2.x 4.4-Lite 3.2.4 1.x to 2.x & 1994 FreeBSD (System V 1994 1.0 to Lite Release 2 R4.2) 1995 2.2.x NetBSD 1995 OpenBSD OpenServer 1.1 to 1.2 Solaris 1.0 to 2.2 5.0 to 5.04 1996 2.1 to 9 1996 1997 1997 NetBSD 1.3 1998 FreeBSD 1998 3.0 to 3.2 OpenServer 1999 Minix 1999 Mac OS X 5.0.5 to 5.0.7 2.x Server 2000 2000 2001 to 2004 AIX 2001 to 2004 Linux 3.0-7.2 2005 2.x UnixWare 2005 7.x 2006 to 2007 (System V 2006 to 2007 R5) 2008 Solaris 2008 10 OpenServer Mac OS X, 2009 OpenBSD 6.x 2009 OS X, FreeBSD NetBSD 2.3-6.8 HP-UX 2010 macOS 3.3-12.x 1.3-8.1 2010 11i+ Minix 10.0 to 10.15 DragonFly 2011 3.1.0-3.4.0 (Darwin BSD 2011 1.2.1 to 19) 1.0 to 4.8 Linux OpenSolaris 2012 to 2015 2012 to 2015 3.x & derivatives (illumos, etc.) 2016 2016 Solaris Linux 11.0-11.4 2/26 2017 2017 4.x OpenServer 2018 10.x 2018 Linux 5.x 2019 2019 Unix Operating Systems Unix/Linux Surprising/New Features Multi-User multiple users work concurently (terminals); root user Multi-Tasking/Time-Sharing multiple tasks run concurently Hierarchical filesystem – tree structure with root "/" everything is a file (directory, device, . ) Software Management Tools and Repositories Linux distributions have software management tools and repositories with ability to install/update software automatically since mid 90s (1997 RPM, 1995 dselect) Android Store comes in . 2008 Windows Store comes in . 2012 How you search for a new software (or updates)? 3/26 Unix Operating Systems How To Start . for Windows Users connect to a remote machine (our case!) select a Linux Distribution and install it: allong your Windows Installation (dual-boot) in a virtual environment (e.g. VirtualBox) Windows Subsystem for Linux currently, there are more than 500 actively developed Linux Distributions2 2https://www.tecmint.com/linux-distro-for-power-users/ 4/26 Unix Operating Systems Linux Distributions Popular in Industry (EDA) Red Hat Enterprise Linux (RHEL) CentOS – RHEL "clone" SUSE Linux Enterprise (SLE) (Oracle Linux) 5/26 Unix Operating Systems Linux Distributions Popular for Home Use Fedora – driven by community around RedHat ("test enviroment" for RHEL) OpenSUSE – driven by community around SUSE Ubuntu – commercial but free (with a paid support option) Debian – greatest community driven distribution Many others: Linux Mint, Slackware, Gentoo, Arch, . 6/26 Command Line Interface – CLI Why to Use . How to Use . 1 Aims of this Lecture Shell Command Language – Unix 2 Unix Operating Systems Standard SSH – Secure Shell 3 Command Line Interface – CLI 4 (Our) BASH Reference It is Used for . 7/26 Command Line Interface – CLI It is Used for . traditional interface for interactive access to computers (super)computer terminals starting in the mid-1960s PCs in/since 1980s nowedays mostly (typical terminal host systems) servers and supercomputers – standardized embedded devices – standardized (e.g. AT) or custom/proprietary (e.g. KETCube) network equipment – routers, probes, . R&Ds personal computers – often mix TUI & GUI for efficiency & automation 7/26 Command Line Interface – CLI Why to Use . less resources remote access, terminal access . ! "embedded" scripting – automation & repetitive tasks CLI vs. script language: program execution vs. function call; work with text vs. work with data (objects) efficient work with files & text filter certain lines from a huge csv file (Excell will crash!) browse & search log files bulk file rename software execution control handle return value access "hidden" features ... 8/26 Command Line Interface – CLI How to Use . Terminal (emulator) HW device to access a terminal host system SW application (terminal emulator), that mimics HW terminal mostly on PC Command Interpreter: Exec CMD Prompt example – (ba)sh: [jan@host]:/home/jan$#[user@host]:path$ PROMPT Exec Batch Prompt example – KETCube: Assign variable >> 9/26 Command Line Interface – CLI Shell Command Language – Unix Standard shell is a command interpreter there are many Shell Command Language implementations with a superset of features sh (Bourne SHell), bash (Bourne Again SHell) – most popular ash (Almquist SHell), dash (Debian Almquist SHell) – leightweight, scripts (may be) compatible with bash csh (C shell), tcsh – increased readability (scripting!); C-inspired syntax sh is nowedays a link to (in most cases) bash, tcsh or dash We will discover only a small part of the Unix tool universe: Many details are hidden or simplified intentionally! 10/26 Command Line Interface – CLI SSH – Secure Shell the cryptographic network protocol – establishes a secured client-server connection/channel capabilities (openSSH, SSHv2): remote SHell & tunneling user authentication by password/private-public key pairs Secure Copy (SCP) and File Transfer (SFTP) protocols Software support: Un*x: openSSH client/server (ssh, sshfs, scp) Windows: Putty, WinSCP $ ssh [email protected] -i .ssh/id_rsa# access remote with $# pub/priv. key pair $ ssh -L8080:localhost:80 ws.net# access ws.net:80 $# from localhost:8080 $ ssh -X [email protected] xeyes# display xeyes locally 11/26 (Our) BASH Reference Filesystem Tree – Logic Filesystem 1 Aims of this Lecture Standard Unix Tools – Filesystem 2 Unix Operating Systems Standard Unix Tools – Text (Files) and Filters 3 Command Line Interface – Standard Unix Tools – CLI Control Flow Standard Unix Tools – 4 (Our) BASH Reference Get Help Command Execution Bash Tricks Builtin Commands Midnight Commander Shell Variables Tricks 12/26 (Our) BASH Reference Command Execution standard output (default is screen) standard input standard error output PROCESS (default is keyboard) (default is screen) ? CMD [parameters] > output < input inputs may be redirected from file: {< , «} outputs may be redirected to file: {> , »} commands may be concatenated: {; , &&, ||, ...} cmd1 ; cmd2 – run cmd1, then run cmd2 cmd1 | cmd2 – filter cmd1 && cmd2 – run cmd2 only if cmd1 OK cmd1 || cmd2 – run cmd2 only if cmd1 ERROR 12/26 (Our) BASH Reference Builtin Commands source – source file echo – print args to stdout pwd – get absloute path of the working directory exit – exit shell + return value 13/26 (Our) BASH Reference Builtin Commands $ source .bashrc $ $pwd / home / jan $ $ echo Hello World! Hello World! $ d bash: d: Command not found... $ alias d="date" $ d Po 2. listopadu 2020, 15:39:00 CET $ $ exit0# no error 14/26 (Our) BASH Reference Shell Variables Important variables: HOME – The current user’s home directory PATH – list of directories in which the shell looks for commands PS1 – prompt definition ? – last command status 15/26 (Our) BASH Reference Shell Variables $ echo $HOME / home / jan $ $ echo $PATH / usr /local/bin:/usr/local/sbin:/usr/bin:/usr/sbin $ $ PATH=${PATH}:/sbin# add new directory toPATH $ echo $PATH / usr /local/bin:/usr/local/sbin:/usr/bin:/usr/sbin:/sbin $ $ echo $PS1 [\u@\h \W]\$# special characters are evaluated byBASH $ 16/26 (Our) BASH Reference Filesystem Tree – Logic Filesystem relative path: ../.. absolute path: / / HDD0 etc home dev bin usr mnt ... HDD1 bin local nfs working directory relative path: .