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It's All Text

First:

In the most simple terms, the essence of free software and free culture is the freedom to fork, which is to say, to take a work, make a copy of it, and work on it as if it were your own.

The question is:

What is the form of that work?

The question is:

What is the form of that work?

For software in particular, it's almost always all text.

So, what are we talking about?

So, what are we talking about?

  • code
  • configuration
  • communication
  • documentation
  • (some) protocols
  • (some) data

Code

Visual programming is rare, but it exists:

  • Scratch
  • Piet

Usually, though, not just text, but English text with no diacritics or accents

  • ASCII
  • Unicode

non-Roman alphabets:

  • Qalb

Configuration

  • dotfiles
  • ini files
  • plists

Documentation

  • "plain" text (see Unicode)
  • various forms of markup
  • reStructuredText
  • Markdown
  • HTML
  • XML
  • TeX
  • YAML
  • JSON

(some) Protocols

  • SMTP
  • HTTP
  • SQL
  • IRC

(some) Data

  • markup (see above)
  • CSV
  • PDB v. mmCIF

Communication

Subscribe to my YouTube channel!

Video can be tedious to make, search, index, sit through, annotate, edit.

(maybe difficulty in editing is its one true advantage)

picture == 1K words ?

Note

They say a picture is worth a thousand words, but how many pictures does it take, for instance, to depict a novel? War and Peace miniseries 6 x 60-80 m at 24 fps? That's a lot of pictures (and audio, too!)

How do we work with all this text?

How do we work with all this text?

command line interface (CLI)

Command-line interface

A CLI is a character addressable interface

Sometimes, but often not, linear, as such.

Also known as:

  • Console
  • terminal

(compare with GUI)

Why Linux/Unix CLI?

Unix paradigm has survived and adapted for 45 years.

Consistent, constant, stable and widespread way of interacting with the computer.

Efficient and precise. You can issue the commands to the computer, you can record it exactly, you can convey to someone else exactly.

Tools for text in a console

  • Editors
  • Pagers
  • Interpreters
  • Compilers
  • servers and clients (see protocols above)

Editors/IDEs

  • vi/vim
  • emacs
  • joe
  • nano
  • pico

Non-console

  • IDLE
  • Jupyter/iPython
  • Notepad++
  • TextMate
  • Atom

Pagers

  • pg
  • more
  • less

Interpreters

REPLs

  • Lisp et al
  • BASIC
  • Forth
  • Python
  • Ruby
  • Lua
  • R
  • sqlite3
  • mysql
  • bash et al

Compilers

  • FORTRAN
  • COBOL
  • C/C++
  • Java(ish)
  • Haskell
  • Go
  • Rust
  • Swift

Servers and clients

(see protocols above)

  • mail
  • mutt
  • elm
  • pine
  • mh
  • bsd-mailx
  • browser
  • lynx
  • w3m
  • links
  • IRC
  • weechat
  • irssi

Now, for some basics

Finding the terminal

  • In Sugar: List view (Ctrl-2) -> choose the start next to Terminal activity
  • Generic Linux virtual terminal: Ctrl-Alt-Fn usually for n=1..6. Switch amongst VTs with Alt-Fn. Alt-F7 back to X (the GUI).
  • Terminal on MacOS
  • Cygwin, gitbash, or babun (Win)
  • Remote terminal via ssh, PuTTY (Win)
  • Termux (Android >=5)

Navigation commands

  • pwd -- print working directory -- where am I?
  • cd -- change directory -- I want to go somewhere else?
  • ls -- list -- what's here?

Pagers

  • more -- run-of-the-mill paging, hit space to continue
  • less -- advanced pager with ability to backup (b), doesn't fall off until explicit quit (q)
  • pg -- a two-letter command, of course

Documentation

  • man ls
  • apropos rename

Composing pipelines

The simplest programs: pipelines

  • ls -al | less

    STDOUT STDIN STDERR

The pipe character '|' is used to send the output of the preceding command into the following command. Simple programs aka "one-liners".

Several commands can be strung together.

Several commands can be strung together.

find . -maxdepth 1 -type d  -name "*_files" -print0 | \
xargs -0 -n1 -i basename {} _files | \
xargs  -n1 -i echo mkdir web-saved/{} \; \
mv {}_files web-saved/{} \; mv {}?* web-saved/{} > web-saved/files_files2.sh

Filtering

  • grep
$ /usr/share/dict/words | grep [A-Z] | less

Simple regular expressions & globs

  • ^ start
  • $ end
  • ? single character
  • * glob of characters

Making changes

Line and history editing

  • history -- show commands you've issued

  • Use up and down arrows to move around history

  • Use tab completion to save typing

  • ctrl-a to beginning of line, ctrl-e to end of line

    • !n -- nth from history,
    • !! -- previous from history
    • !* -- 1st token from previous
    • !$ -- all but 1st from previous
    • ^f^b^ -- sub b for f in previous

Making changes: Retail

Text editors

  • examples:
  • nano/pico
  • vi
  • emacs
  • survival commands: (how to exit)
  • ctrl-x
  • Esc Esc Esc :q!
  • Ctrl-x Ctrl-c

Redirection

to create or overwrite a file use >

echo foo > bar; cat bar

to create or add to a file use >>

echo quux >> bar; cat bar

Take command

Processes and job control

See what's going on

* ps -- list processes

* top -- show and compare resource usage

* jobs -- show jobs and their state

Take command

Processes and job control

Change what's going on

  • ctrl-c -- kill (permanent)
  • ctrl-z -- suspend (temporary)
  • fg -- foreground
  • bg -- background
  • nice -- lower priority
  • time -- how long?
  • kill -- end a process

example -- "Help, firefox is out of control!"

Making changes: Wholesale

Whole files & directories

  • cp -- copy
  • rm -- remove -- delete CAUTION NO RECOVERY GONE FOR GOOD
  • mv -- move -- also rename

Usage Examples:

  • cp a way to make a backup file, say, of /etc/apt/sources.list
  • rm the editor's backup files eg foo~
  • mv as a way to rename image files, say, a cryptically named image file

Querying system state

hardware

"extended" ls commands

  • dmesg -- display kernel mesages
  • lsmod -- kernel modules
  • lspci -- pci bus devices
  • lsusb -- usb devices
  • lshal -- hardware access layer
  • lshw -- hardware

Querying system state

installed software (Debian & Ubuntu)

  • dpkg -l | less -- show all packages
  • dpkg -L nano | less -- show files in a package
  • dpkg -S /usr/bin/nano -- this file belongs to which package?
  • apt-cache search foo
  • apt-get install foo

Querying system state

installed software

(Redhat, Fedora, SoaS, et al)

  • rpm -qa -- show all packages
  • rpm -ql nano | less -- show files in a package
  • rpm -qf /usr/bin/nano -- this file belongs to which package?
  • yum search foo
  • yum install foo
  • dnf

Filesystem hierarchy and status

LSB /bin, /sbin, /etc, /home, /lib, /usr/bin, /usr/sbin, /usr/lib ...

System state

  • df -- disk free
  • du -- disk usage
  • netstat -- network status
  • less /proc/cpuinfo
  • less /proc/meminfo
  • ifconfig
  • ls /var/log
  • ls /etc

Environment variables

  • echo $HOME; echo $PATH -- show two most common
  • env -- show all environment variables
  • set FOO=bar; echo $FOO

Further topics

  • advanced grep (context, case), wc, with lsmod and ps
  • less -N -- numbering
  • find foo -name "bar*" | xargs -n1 -i echo {} ;
  • chown newuser:newuser foo changing ownership
  • chmod go+r foo change access mode (permissions)
  • rsync -- convergent synchronization (local or over net)
  • scp -- remote (secure) copying
  • ssh -- remote login
  • screen & tmux -- detachable & re-attachable cli session
  • others: lynx w3m wget curl links -- CL web tools
  • others: head tail split cut -- slicing and dicing text
  • alternate shells: csh, tcsh, ksh, zsh, ash, dash