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Ask your administrator if you think this is wrong. ====== History ====== ==== Unix — Linux’ predecessor ==== > Unix is from the ’70s: * terminals are monochrome * computers are big and expensive * many people use the same computer * networking becomes important > Unix is free to modify: * universities and companies have modified unix * released as BSD/Solaris/HP-UX/IRIX * fertile environment * rise of similar, non-collaborating features > Unix becomes the GCD of computing. ==== Hacker culture ==== > Freedom at stake: * the way of sharing programs is changing * best case: bsd-style license * usually: corporate licenses * exclude freedom of sharing code with anyone > Sharing is caring: * write code * give away/sell product * include **sourcecode** * include the freedom/restriction to do share code under the same license > People want to save their idea of moral responsibility by formalising it as a licenses ==== GNU ==== {{.:gnu.svg?0x200}} > In 1984 RMS starts the **GNU** project, with the goal to provide a **free Unix**-compatible OS > Steps to success: * Write a license (GPL) * respect the freedom of the users * endorse ‘sharing is caring’ * make the license transitive * Write an Editor (emacs) * Write a Compiler (gcc) * Write common utilities (coreutils) * Write everything else * Write a kernel (hurd) * Rewrite the kernel (hurd) * One more time (hurd) > Even though this project gets mocked for hurd, it is essential for Linux’ success! ==== Linux ==== {{.:gnu_tux.svg?0x220}} > In 1992 Linus Torvalds writes his own little **terminal emulator**, to be able to remotely access his university account. > Later this code evolves into the **Linux kernel**, that together with many **GNU utilities** becomes **GNU/Linux** — a.k.a Linux ^Segment ^ Linux variant ^ Market share ([[https://en.wikipedia.org/wiki/Usage_share_of_operating_systems#Market_share_by_category|Source]])^ |Desktop | Debian / Fedora / Arch / … | ~2%| |Smartphone / Tablet| Android | ~70%| |Server | Debian / RHEL / Gentoo / … / CUSTOM | ~65%| |**Supercomputer** | **CentOS** / CUSTOM | ~99%| |Mainframe | RHEL / SLES | ~30%| |Embedded | Android / … | ~30%| ==== Linux on Supercomputers ==== {{.:os_supercomputers.svg}} ====== Prerequisites ====== ==== Assumptions ==== > You are familiar with either: * **computers** in general * **Windows** * **macOS** > When something breaks, you: * ask for **assistance** //or// * **read** up on the subject and **fix it** //and// * **don’t** go on **using** it until it’s completly **dead** ==== What do you know about Linux? ==== > by a show of hands: {{.:tux.svg?0x500}} * Nothing * I know my way around when it comes to: * files and directories * the shell basics * most core utilities * variables * scripts * streams * All of the above and I want to take over ====== Filesystems ====== ==== Filesystem 101 ==== - Everything starts at the root * the root is a directory * ''%%/%%'' denotes the root directory - the filesystem has different kinds of objects - files - directories * containers for multiple objects - links to objects, which either * add a second name for the same object * point to a position in the filesystem - objects can be referenced by their path * absolute: ''%%/dir1/dir2/object%%'' * relative: ''%%dir2/object%%'' - special objects in directories: * ''%%.%%'' — is a reference to the directory itself * ''%%..%%'' — is a reference to the parent directory - the system may consist of multiple filesystems * filesystems may be mounted at any (empty) directory ==== The Filesystem represented as an ADT ==== > These are the helper types: <code> type Name = String type Children = [FSObject] type Path = [FSObject] data LinkType = Soft | Hard </code> > This is the code describing a trivial Linux-ish filesystem in a mathematical notation: <code> data FSObject = File Name | Dir Name Children | Link Name Path LinkType </code> > Missing: * Special files * device * fifo pipe * socket * Attributes * Advanced FS features * data integrity * device managment * subvolume support ==== FHS intro ==== {{.:linux_directories.jpg}} ==== FHS ==== > The **Filesystem Hierarchy Standard** is a guideline for the structuring of local filesystems. It aims for better **interoperability** between different Systems, by making it easy to figure out the **location** of any **kind of file**. ^Directory ^Purpose ^ |**/** |root of the hierarchy | |**/bin/** |basic binary files | |**/boot/** |files for boot support | |**/dev/** |virtual files, for direct access to devices | |**/etc/** |system-wide confidurations - historical, misleading name | |**/home/** |users’ home direcories are located here | |**/lib/** |library files for ''%%/bin/%%'' ''%%/sbin%%'' | |**/media/**|removable media mounts | |**/mnt/** |temporary mounts | |**/opt/** |optional applications | |**/proc/** |system-internals accessable as files | |**/root/** |home directory of root | |**/run/** |variable data should be removed while booting | |**/sbin/** |like ''%%/bin/%%'', but require special permissions | |**/srv/** |data served to other systems | |**/sys/** |statistics about devices | |**/tmp/** |temporary files, can be removed while booting | |**/usr/** |most higher level applications are inside, looks a lot like ''%%/%%''| |**/var/** |files that change often (cache/db/log/mail/…) | ==== Corner cases of FHS ==== > Some systems don’t comply with the FHS, for various reasons. === VSC3 === * As the OS is basically a CentOS, the ''%%/lib/%%'' and ''%%/lib64/%%'' are just symlinks === Distributions bringing new ideas to the table === > [[http://gobolinux.org/|GoboLinux]]: * installed software packages get their own directory * filesystem itself is a package store > [[http://nixos.org/|NixOS]]: * solves the problem of user installable packages * dependency management extended in a way, that aims to make trust a non-issue ====== Shell ====== ==== Login ==== > The default login screen on most distributions looks something like this: <code> <<< Welcome to ${DISTRO} - tty{1..6} >>> ${MACHINE_NAME} login: password: </code> <code> username <blank while typing> </code> <HTML> <div class="incremental"> <div> <hr style="clear: both;"> </HTML> > remote login looks similar: <code bash> $ ssh username@remote password: </code> <HTML> </div> <div> <hr style="clear: both;"> </HTML> {{.:tango_locked.svg?0x100}} {{.:tango_unlocked.svg?0x100}} <HTML> </div> </HTML> > If the login was not successful, just try again. > Beware, that systems may be configured to lock your account if too many attempts were made. <HTML> </div> </HTML> ==== Prompt ==== > This is how the prompt looks by default: {{.:tango_terminal.svg?0x100}} <code bash> [myname@l3_ ~]$ </code> * tells you: * who you are * which computer you’re on * which directory you’re in * can be configured * variable ''%%$PS1%%'' * default: ''%%echo $PS1%%'' > Ways to get help when you’re stuck: * ''%%man%%'' * manual for specified topic * find man-pages: ''%%apropos%%'' * ''%%whatis%%'' * ''%%info%%'' * most commands support a ''%%-h%%''/''%%--help%%'' flag * colleagues are often helpful * the internet is often helpful ==== Execution ==== To execute a program, we call it: <code python> nano file.txt ./a.out -flag=value gcc -I/home/lv12345/myuser/include module load non-existent-module </code> * Every command that is executed will provide a return-value on exit. * {{.:tango_ok.png?0x30}} A value of ''%%0%%'' means success * {{.:tango_cancel.png?0x30}} any other value means failure === Program Arguments === > The default way to apply arguments to a program is to write a space separated list of arguments after the program when calling it. > Patterns and expansions are defining multiple arguments with little overhead: * the most important patterns are: * **?** — matches one character * ***** — matches any character sequence * the most important expansions are: * **A{1,9}Z** — expands to A1Z A9Z * **A{1..9}Z** — expands to A1Z A2Z … A9Z ==== Control Flow ==== === Chaining Commands === <code bash> false ; echo "Should I be Printed?" false && echo "Should I be Printed?" false || echo "Should I be Printed?" </code> <code bash> Should I be Printed? Should I be Printed? </code> === Loops === <code bash> for i in * do mv $i{,.bak} done </code> <code bash> while true do echo "Annoying Hello World" sleep 3 done </code> > Or as one-liners: <code bash> for i in *; do mv $i{,.bak}; done while true; do echo "Annoying Hello World"; sleep 3; done </code> ==== Aliases ==== Whenever you have a command, which you: - run often and it * has a long list of parameters you always use * is dangerous - which is an aggregate of many other commands * but you don’t want to write a script you can define an alias for it: <code bash> alias ll='ls -alh' alias myProject='cd $ProjectDir; testSuite; compile && testSuite; cd -' </code> ==== History ==== {{.:tango_search.svg?0x100}} > Your shell keeps a log of all the commands you executed. * the ''%%history%%'' command is used to access this history * for fast reuse of commands try the ''%%<CTRL>-R%%'' keys ==== Streams ==== === Redirects === > Write **output** to a **file** or **file-descriptor** ^Command^Redirect ^Append ^Description ^ |program|''%%> std.log%%''|''%%>> std.log%%''|redirect ''%%stdout%%'' to a file | |program|''%%2> err.log%%''|''%%2>> err.log%%''|redirect ''%%stderr%%'' to a file | |program|''%%2>&1%%'' | |redirect ''%%stderr%%'' to ''%%stdout%%''| === Pipes === > Write **output** into the **input**-stream of another process ^Command^Pipe ^Description ^ |program|''%%| grep -i foo%%'' |pipe ''%%stdout%%'' into ''%%grep%%''| |program|''%%| tee file1 file2%%''|overwrite files and ''%%stdout%%'' | |program|''%%| tee -a file%%'' |append to files and ''%%stdout%%'' | ====== Environment Variables ====== ==== Setting, getting and unsetting ==== === Set === <code python> LANG=de_AT.UTF-8 firefox env LANG=de_AT.UTF-8 firefox </code> <code python> export LANG=de_AT.UTF-8 </code> === Get === <code python> env echo ${LANG} </code> === Unset === <code python> unset LANG env -u LANG </code> ==== Use cases ==== > Some variables that could affect you are: <code python> $EDITOR # the default editor for the CLI $PAGER # utility to read long streams $PATH # program paths, in priority order </code> > if you’re aiming for programming, these could be more interresting: <code python> $LIBRARY_PATH # libraries to link by the compiler $LD_LIBRARY_PATH # libraries to link at runtime $CC # sometimes used to set default C compiler $CFLAGS # default flags for compiling C </code> ====== Core Utilities ====== ==== Looking around ==== > **looking around** is done by the **''%%ls%%''** (list) command <code> $ ls # shows files and directories $ ls -a # includes hidden ones $ ls -l # detailed view </code> <code> testdir test . .. testdir test drwxr-xr-x 1 myuser p12345 0 Apr 13 11:55 testdir -rw-r--r-- 1 myuser p12345 4 Apr 13 11:55 test </code> {{.:linux_directories.jpg?0x400}} ^command ^ result^ |**''%%ls /%%''** | ''%%bin dev etc home sbin usr%%''| |**''%%ls /home%%''** | ''%%user1 user2%%''| ==== Moving around ==== > **moving around** is done by the **''%%cd%%''** (change directory) command > **finding** the current **position** in the filesystem is done by the **''%%pwd%%''** (print working directory) command <code> $ cd /bin # go to an absolute directory $ cd [~] # go home $ cd - # go to previous directory </code> <code> $ pwd # /bin $ pwd # /home/user1 $ pwd # /bin </code> {{.:linux_directories.jpg?0x400}} ==== Copying & moving files around ==== > **moving files around** is done by the **''%%mv%%''** (move) command > **copying** is done by the **''%%cp%%''** (copy) command <code> $ mv old new # rename old to new $ mv old dir/ # move old into dir $ mv file1 file2 # overwrite file2 with file1 # (BEWARE) </code> <code> $ cp -i input input.bak # input to input.bak $ cp -i input backup/ # input into backup $ cp -a dir1/ dir2 # exact copy of dir1 </code> {{.:screenshot_mv.png?0x350}} {{.:screenshot_cp.png?0x350}} ==== Finding stuff ==== > To look at everything - in your home directory - and nested up to three levels deep inside it - that ends in ''%%.txt%%'' - or starts with ''%%log_%%'' - and is an ordinary file - concatenated as one stream: <code bash> find \ ~ \ -maxdepth 3 \ -iname "*.txt" \ -or -iname "log_*" \ -type f \ -exec cat '{}' \; | less </code> <code bash> find \ ~ \ -maxdepth 3 \ -iname "*.txt" \ -or -iname "log_*" \ -type f \ -exec cat '{}' + | less </code> ==== Creating and deleting ==== === directories === > **creating directories** is done by the **''%%mkdir%%''** (make directory) command: > **deleting directories** is done by the **''%%rmdir%%''** (remove directory) command: <code bash> $ mkdir newdir # create directory newdir $ mkdir -p new/dir # create dir inside of new </code> <code> $ rmdir emptydir # removes emptydir $ rmdir -v emptydir # removes emptydir (verbose) </code> === files === > **creating files** is done by the **''%%touch%%''** or **''%%echo%%''** commands: > **deleting files** is done by the **''%%rm%%''** (remove) command: <code bash> $ touch file # create empty file $ echo "abc" > file # create/overwrite file </code> <code> $ rm file # removes file $ rm -ri dir # removes dir recursively </code> ==== Contents of files ==== > **viewing** is done by the **''%%less%%''** command: > **concatenating** is done by the **''%%cat%%''** command: <code> $ less file.txt # exit with 'q' $ less -R file.txt # keep colors $ cat file1 file2 | less </code> <code> $ cat file $ cat -A printable $ cat -n numbered </code> <code> $ echo "VSC is great" > file $ cat file VSC is great </code> <code> $ echo "VSC is awesome" >> file $ cat file VSC is great VSC is awesome </code> <code> $ cat file | grep awesome VSC is awesome </code> <code> $ grep awesome file VSC is awesome </code> ==== Space accounting ==== > viewing **used space** is done by the **''%%du%%''** (disk usage) command: > viewing **free space** is done by the **''%%df%%''** (disk free) command: <code> $ du -h file1 file2 # human readable output $ du -s dir # summarize </code> <code> $ df -h # human readable output $ df -t nfs # only list filesystems of a type </code> {{.:screenshot_df.png?0x440}} ==== Recap ==== <code> $ mv space.log space.log.bak </code> <code> $ df -h | grep "lv12345\|lv54321" > space.log </code> <code> $ cat space.log </code> <code> nfs05.ib.cluster:/e/lv12345 200G 185G 16G 93% /home/lv12345 nfs04.ib.cluster:/e/lv54321 1000G 979G 22G 98% /home/lv54321 </code> > we do this often, let’s wrap it up! ==== Recap++ ==== <code> $ mv space.log space.log.bak </code> <code> $ df -h | grep "lv12345\|lv54321" > space.log </code> <code> $ cat space.log </code> <code> nfs05.ib.cluster:/e/lv12345 200G 185G 16G 93% /home/lv12345 nfs04.ib.cluster:/e/lv54321 1000G 979G 22G 98% /home/lv54321 </code> > we do this often, let’s wrap it up! <code> $ echo '#!/bin/bash' > spacelog.sh $ echo 'mv space.log space.log.bak' >> spacelog.sh $ echo 'df -h | grep "lv12345\|lv54321" > space.log' >> spacelog.sh $ echo 'cat space.log' >> spacelog.sh </code> <code> $ chmod +x spacelog.sh </code> <code> $ ./spacelog.sh </code> ==== Sed and awk ==== > **sed** (stream editor) and **awk** are powerful tools when working with the command line <code> $ mycommand | sed "..." </code> <code> $ mycommand | awk '{...}' </code> > Using sed and awk in action ^program ^ command ^description ^ |sed | ''%%s/old/new/%%'' |replace ''%%old%%'' with ''%%new%%'' | |sed | ''%%/from/,/to/ s/old/new/%%'' |replace ''%%old%%'' with ''%%new%%'', between ''%%from%%'' and ''%%to%%'' | |awk | ''%%'print $5, $3'%%'' |print columns 5 and 3 of every line | Example script: <code bash> #!/bin/bash mv space.log space.log.bak df -h | grep "lv12345\|lv54321" > space.log cat space.log </code> <code bash> #!/bin/bash mv space.log space.log.bak df -h | grep "lv12345\|lv54321" > space.log cat space.log | sed "s|/home/lv12345|ProjectA|" \ | awk '{print $6, "free:", $4}' \ | column -t </code> ====== Scripting ====== ==== Ownership and Permissions ==== > Just to ensure, that you are able to run your scripts === chown === > Change the owner of files and directories by: <code bash> chown -R user:group dirs files </code> === chmod === > Change the mode of files and directories by: <code bash> chmod -R u=rw,g+w,o-rwx dirs files chmod -R 644 dirs files </code> ==== Shebang ==== A little test program, which we mark as executable and hand it over to the corresponding interpreter: <code bash> cat << EOF > test.sh echo "${LANG}" echo "${PATH}" EOF </code> <code bash> chmod +x test.sh </code> <code bash> bash test.sh </code> > Don’t we have an OS, capable of executing everything it recognises as a executable? > Yes, we do! <code bash> cat << EOF > test.sh #!/bin/bash echo "${LANG}" echo "${PATH}" EOF </code> <code bash> chmod +x test.sh </code> <code bash> ./test.sh </code> ==== Functions (more like Procedures) ==== Programming in bash would be cumbersome without functions, so here we go: <code bash> printAllNumbers () { echo "1 2 3" echo "done" } </code> === Arguments === > This isn’t good, as were only getting a fixed amount of numbers. let’s try a recursive approach <code bash> #!/bin/bash printAllNumbersFrom () { num=$1 echo "${num}" printAllNumbersFrom "$(($num + 1))" } printAllNumbersFrom $2 </code> ====== Editors ====== ==== General ==== * Many different editors * Unique (dis-)advantages * Different look and feel * Editors should provide us with - Simple text editing - Copy and paste - Search and replace - Saving changes - Wide availability === Two editors that satisfy our needs: === * nano * vim === Common starting point === <code bash> nano filename </code> <code bash> vim filename </code> ==== Nano ==== {{.:screenshot_nano.png}} ==== Nano explained ==== > This editor is focused on being easy to use, but still providing every feature a user might need. === Interface === > The interface consists of four parts, namely from top to bottom: * Title bar * Text area * Command line * Key bindings === Usage === > Nothing special, key-bindings visible while editing ^Feature ^ Usage ^ |Navigation | Arrow keys | |Actual editing| Typing text, as usual | |Cut/Paste line| ''%%<CTRL>%%''+k / ''%%<CTRL>%%''+u | |… | explained in key bindings field | === Short === > Use this editor if you are new to the command line.\\ > It is straight forward, but can be extended on the way. * Auto-indentation * Syntax highlighting * Multi-buffer {{.:screenshot_nano.png?0x300}} ==== Vi(m) ==== {{.:screenshot_vim.png}} ==== Vi(m) explained ==== > This editor is focused on productivity and efficiency, providing everything a user might need. === Interface === > The simple interface consists of two parts: * Text area * Command line > Since this editor is very easy to extend, after setting up a few plugins, it will probably look quite different! === Usage === > This is a multimode editor, you’ll have to switch modes whenever you change what you want to do. ^Feature ^ Usage ^ |Navigation| hjkl / Arrow keys | |Writing | change to input mode, then write as usual | |Commands | exit current mode, press ''%%:%%'' | |… | explained on next slide | === Short === > Use this editor if you like a challenge.\\ > It is fast and very nice — but you’ll sometimes get hurt on the way. * Auto-indentation, Syntax highlighting, Multi-buffer – just like nano * File/Project Management * Use a plugin manager {{.:screenshot_vim.png?0x300}} ==== Vi(m) modes and keys ==== * any mode: * back to the **default mode**: **''%%<ESC>%%''** * command mode (followed by ''%%<RETURN>%%''): * **save** current file: **''%%w [filename]%%''** * **quit** the editor * after saving: **''%%q%%''** * without confirmation: **''%%q!%%''** * **help**: **''%%h [topic]%%''**, e.g. **''%%h tutorial%%''** * **search and replace**: **''%%%s/old/new/gc%%''** * //default mode//: * enter **input mode**: **''%%i%%''** * enter **command mode**: **''%%:%%''** //(colon)// * **mark** * **character**-wise: **''%%v%%''** * **line**-wise: **''%%<SHIFT>-v%%''** * **delete** * **character**-wise: **''%%x%%''** * **line**-wise: **''%%dd%%''** * **marked content**: **''%%d%%''** * **search**: **''%%/abc%%''** ====== QED ====== ==== Fin ==== {{.:tux_banner.png?0x600}} * Questions? * Need help installing Linux? * Contact: <Email> <HTML> <!-- > Public domain: - [Ubuntu Tango Icons](https://wiki.ubuntuusers.de/Wiki/Icons/Tango/) > Mixed (CC, public domain, ...) - [Wikipedia Tango Icons](https://commons.wikimedia.org/wiki/Tango_icons) # Timers ## Systemd Units ## Systemd Timers ## Putting it together ## Background ### What is GNU/Linux {.incremental} {height=200px style="float: left;" .incremental} <div class="columns"> > - It's a collection of Software, including: > - **Linux** itself, as the `kernel` > - basic tools, mostly from the **GNU** project > - additional, specialised software for most tasks > - the **OS** that powers the internet, the mobile world and more > - **opensource** and **free software** effort to retain essential freedoms of the user </div> ### Reasons for Linux {.incremental} {height=200px style="float: right;".incremental} <div class="columns"> > - Wide Adoption > - Stable platform > - Anyone can try and use Linux > - Easy adaption to custom environments </div> ### Basic Usage {.incremental} {height=200px style="float: left;" .incremental} <div class="columns"> > - using and understanding the shell > - moving through the directory structure > - moving files and directories > - editing files > - writing and executing scripts > - environment and variables </div> ## CLI Basics <div class="columns"> ### Shell > The shell used on the VSC is called **bash**. It's the most common shell today, preinstalled by most Linux and macOS versions. > - It's behaviour is controlled by the file **.bashrc** > - loaded at login > - can be customized > - is a shell script > - Has some usability features > - most of the time commands can be auto-completed by pressing `TAB` > - can recall history with `CTRL-R` or `history` > - Provides a full programming language/environment > - can do native processing of Strings, Integers and Arrays > - can execute any program > - is turing-complete, but not considered a general-purpose language ### Environment > The shell and some default tools are configured through **variables**. > - list variables with `env` > - modify them with `export X=Y` > - get the content by prepending it with a dollar sign `$A` > - useful in scripts <div class="incremental"> Some variables that could affect you are: ``` $EDITOR # the default editor for the CLI $PAGER # utility to read long streams $PATH # program paths, in priority order ``` </div> </div> ## Executing Commands <div class="columns"> <div class="incremental"> To execute a program, we call it: ```{.bash} nano file.txt ./a.out -flag=value gcc -I/home/lv12345/myuser/include module load non-existent-module ``` </div> > - Every command that is executed will provide a return-value on exit. > - {height=30px} A value of `0` means success > - {height=30px} any other value means failure </div> ### Program Arguments {.incremental} <div class="incremental"> > The default way to apply arguments to a program is to write a space separated list of arguments after the program when calling it. > Patterns and expansions are defining multiple arguments with little overhead: </div> <div class="columns"> > - the most important patterns are: > - **?** --- matches one character > - **\*** --- matches any character sequence > - the most important expansions are: > - **A{1,2}Z** --- expands to A1Z A2Z > - **1{a..z}A** --- expands to 1aA 1bA ... 1zA </div> ### Chaining Commands {.incremental} <div class="columns incremental"> ``` {.bash .numberLines} false ; echo "Should I be Printed?" false && echo "Should I be Printed?" false || echo "Should I be Printed?" ``` ``` {.bash .numberLines} Should I be Printed? Should I be Printed? ``` </div> <!-- - - - ### Using Patterns and Expansions {.incremental} <div class="columns"> > - the most important patterns are: > - **?** --- matches one character > - **\*** --- matches any character sequence > - the most important expansions are: > - **A{1,2}Z** --- expands to A1Z A2Z > - **1{a..z}A** --- expands to 1aA 1bA ... 1zA </div> --> <!-- ## Loops > look like this in a shell: <div class="columns incremental"> ```{.bash} for i in * do mv $i{,.bak} done ``` ```{.bash} while true do echo "Annoying Hello World" sleep 3 done ``` </div> #### Generating parameters in bash {.incremental} <div class="columns incremental"> ```{.bash} i=1 while [ $i -lt 10 ] do j=1 while [ $j -le $i ] do echo "$i $j" # Your command comes here let j+=1 done let i+=1 done unset i j ``` ```{.bash} 1 1 2 1 2 2 3 1 3 2 3 3 ... 9 6 9 7 9 8 9 9 ``` </div> ## Getting familiar with the CLI <div class="columns"> > This is how the prompt looks by default: ``` {.bash} [myname@l3_ ~]$ ``` {height=190px .incremental} {height=190px .incremental} {height=190px .incremental} </div> <div style="float: left"> #### Prompt {.incremental} > - it's "promting" you to enter a command > - tells you: > - who you are > - which computer you're on > - which directory you're in > - can be configured to show more information > - setting is in a variable called `PS1` > - default value of `$PS1`: `[\u@\h \w]\$` > - can add date, time and the output of custom commands > - see `man bash` for details about your shell </div> <div style="float: right" class="incremental"> #### In case of confusion > there are many ways of getting further: > - the `man` command > - opens the manual for a specified topic > - especially nice to find man-pages: `apropos` > - the `whatis` command > - the `info` command > - is more complex and more like a browser > - most commands support a `-h`/`--help` flag > - colleagues are often helpful > - the internet is often helpful </div> <div style="float: left" class="incremental"> {width=270px .incremental} </div> ## Shell - More than a prompt ### Simple Input/Output <div class="columns incremental"> Any program running in the shell can by default read from the keyboard and write to the screen. We try this with the `cat` command, which is short for concatenate. ```{.bash} cat some text # Input some text # Output <CTRL>-d ``` </div> ### Piping Input/Output <div class="columns incremental"> Since echoing input back to the user isn't particularly useful, we'll be echoing back filtered output. We add a pipe, which redirects the output of the command before it to the command following it, and filter for any line containing `VSC`. ```{.bash} cat | grep VSC 1 2 3 # Input, no Output 1 VSC 3 # Input 1 VSC 3 # Output <CTRL>-d ``` </div> ### Redirecting Input/Output <div class="columns incremental"> Now we can write the resulting stream into a file called VSC.txt. This is done by adding a greater-sign between the end of the command and the filename of the resulting document. ```{.bash} cat | grep VSC > VSC.txt 1 2 3 # Will not be in VSC.txt 1 VSC 3 # Will be in VSC.txt <CTRL>-d ``` <!-- ```{.bash} cat VSC.txt 1 VSC 3 ``` --> <!-- </div> ## Cool Tools ### Less is More <div class="columns"> Since piping output is awesome we want to have a program, that can handle all the output of the other programs and present it in screen-sized parts. Hence the program `less`, which is just `more`. ```{.bash} find ~ -iname "*.txt" -type f -exec cat '{}' \; | less ``` </div> ### Permissions <div class="columns"> If some file can't be accessed/modified, there is a chance that you haven't got the rights to do so. For these cases there is the tool `chmod`, which changes the mode of a file. ```{.bash} chmod a=w file chmod u+x file chmod g-w file chmod o=r file ``` </div> ### Aliasing commands <div class="columns"> you should define an `alias`, whenever there is a command which: - is run with parameters which don't change between runs - has some hard to remember name - needs a non-default safeguard ```{.bash} alias f='find ~ -type f -iname' alias rm='rm -i' alias def-env='cd ~/projectA && \ module purge && \ module load x/1 y/2 z/3' ``` </div> ## Filesystem 101 <div class="columns"> > 1. Everything starts at the root > - the root is a directory > - `/` denotes the root directory > 2. the filesystem has different kinds of objects > 1. files > 2. directories > - containers for multiple objects > 3. links to objects, which either > - add a second name for the same object > - point to a position in the filesystem > 3. objects can be referenced by their path > - absolute: `/dir1/dir2/object` > - relative: `dir2/object` > 4. special objects in directories: > - `.` --- is a reference to the directory itself > - `..` --- is a reference to the parent directory </div> ##### The Filesystem represented as an ADT {.incremental} <div class="incremental columns"> > These are the helper types: ```{.haskell} type Name = String type Children = [FSObject] type Path = [FSObject] data LinkType = Soft | Hard ``` > This is the code describing the trivial Linux-ish filesystem in a mathematical notation: ```{.haskell} data FSObject = File Name | Dir Name Children | Link Name Path LinkType ``` </div> - - - ### Getting and Manipulating our position in the FS <div class="columns"> > - `'ls'`: short for `'list'` > - `'tree'`: tree view of files and directories > - `'pwd'`: short for `'print work directory'` > - `'cd'`: short for `'change directory'` </div> <div class="incremental"> > Example for **looking around**: <div class="columns incremental"> ``` $ ls # shows files and directories $ ls -a # includes hidden ones $ ls -l # detailed view ``` ``` testdir testfile . .. testdir testfile drwxr-xr-x 1 myuser p12345 0 Apr 13 11:55 testdir -rw-r--r-- 1 myuser p12345 4 Apr 13 11:55 testfile ``` </div> </div> <div class="incremental"> > Example for **moving around**, starting at the home directory: </div> <div class="columns incremental"> ``` $ pwd $ cd ..; pwd $ cd /global; pwd $ cd; pwd $ cd -; pwd ``` ``` /home/lv12345/myname /home/lv12345 /global /home/lv12345/myname /global ``` </div> - - - ### Moving files and directories <div class="columns"> > - `'mv'`: short for `'move'` > - `'cp'`: short for `'copy'` </div> <div class="incremental"> > Example: <div class="columns"> ``` $ cp file.orig file.copy $ mv file.orig file.copy $ cp file.orig dir $ mv file.orig dir $ cp dir1 dir2 # ERROR $ cp -r dir1 dir2 # WORKS $ mv dir1 dir2 # WORKS ``` > - copying or moving directories can result in unexpected behaviour: > - if dir2 is an existing directory, dir1 will become a subdirectory of dir2 > - if dir2 is non-existent, dir1 will become dir2 </div> <div class="columns"> ##### Transfer to/from Cluster > - `'scp'`: short for `'secure copy'` > - arguments can be either local or remote files and direcotries > - `'rsync'`: short for `'remote syncronization'` > - similar to regular `mv`/`cp`/`scp`, except: > - pedantic about trailing slashes > - can merge directories > - can delete/overwrite changed files </div> `rsync` seems easy to use, but the advanced options could remove data from both sides of your transfer! It's a **syncronazation** utility, no simple move/copy tool </div> <!-- - - - ##### SCP ``` $ cp file.orig file.new $ scp user@host:dir/file.orig file.new $ scp file.orig user@host:dir/file.new ``` - this is easy to use and preferable for little, one time transfers [ID1]: src/tux.svg "Hover Text 1" {height=150px style="margin: 10px;"} [ID2]: src/tux.svg "Hover Text 2" - ![Test][ID1] - {height=150px style="margin: 10px;"} - [<font color=#cc3300>➠</font>][ID2] - - - ##### RSYNC ``` $ rsync dir1 dir2 # Local copy $ rsync -e ssh dir1 dir2 # Remote copy # These two have the same result: $ rsync dir1 dir2 $ rsync dir1/ dir2/dir1 # This doesn't: $ rsync dir1/ dir2 ``` - there are many useful options, like: - `-a` $\rightarrow$ Archive mode, usually you want this - `-v` $\rightarrow$ Verbose mode - `-p` $\rightarrow$ Preserve permissions - `...` $\rightarrow$ RTFM or don't use those options - the `-e ssh` option tells rsync to connect via ssh to the remote machine - in this case the remote location is written like this: - user@host:remoteDir - trailing slashes have an effect on where your files will go --> <!-- ## Copyleft Third party content and its licensing information can be found at: - [Levitating Gnu](https://www.gnu.org/graphics/meditate.html): - María del Pilar Saenz: [GFDL](https://www.gnu.org/copyleft/fdl.html) - [Tux](https://pixabay.com/en/tux-penguin-animal-cute-linux-158547/): - [CC0 Public Domain](https://creativecommons.org/publicdomain/zero/1.0/deed.en) - [Tux and Gnu](https://commons.wikimedia.org/wiki/File:GNU_and_Tux.svg): - Aurelio A. Heckert: [Free Art License](http://artlibre.org/licence/lal/en/) - Larry Ewing, Simon Budig and Anja Gerwinski: probably [CC-BY](https://creativecommons.org/licenses/by/4.0/) - [Tango Icons](https://commons.wikimedia.org/wiki/Tango_icons ): - Public Domain ## Copyright The not explicitly licensed or non freely-redistributable licensed stuff: - [the Good, the Bad & the Ugly](http://cinetropolis.net/wp-content/uploads/2013/10/the-good-the-bad-and-the-ugly-t-anderson-banner.jpg): - [Dunno]() ## TestStuff 😁 $\rightarrow$ 😄 😁 $\Rightarrow$ 😄 😁 $\longrightarrow$ 😄 😁 $\Longrightarrow$ 😄 https://apps.timwhitlock.info/emoji/tables/unicode#emoji-modal [//]:#(Das ist ein Kommentar, dass nirgends aufscheint) [TuxAndGnu]: https://upload.wikimedia.org/wikipedia/commons/5/53/GNU_and_Tux.svg "Tux and Gnu" [VSC]: https://vsc.ac.at "Vienna Scientific Cluster" ## ToDo - nano/vi - df -h . - du -sh ./* - cat | sort | uniq | tr | awk | sed - example ## table head1 | head2 | head3 :-----|:-----:|-----: p1 | e11 | e12 p1 | e11 | e12e12 p1 | e12e12e12e12e12 | e12 head1 | head2 | head3 :-----|:-----:|-----: p1 | e11 | e12 p1 | e11 | e12e12 p1 | e12e12e12e12e12 | e12 --> </HTML> pandoc/linux-wochen-wien/linux-101/linux-101.txt Last modified: 2020/10/20 09:13by pandoc