Page Comparison

This page should serve as a reference for the many "things Linux" we use in this course. It is by no means complete – Linux is **huge** – but offers introductions to many important topics.

...

• Macs and Linux have a Terminal program built-in
• Windows options:
  • Windows 10+
    • Command Prompt and PowerShell programs have ssh and scp (may require latest Windows updates)
      • Start menu → Search for Command
    • Putty – http://www.chiark.greenend.org.uk/~sgtatham/putty/download.html
      
      • simple Terminal and file copy programs
      • download either the Putty installer or just putty.exe (Terminal) and pscp.exe (secure copy client)
    • Windows Subsystem for Linux – Windows 10 Professional includes a Ubuntu-like bash shells
      • See https://docs.microsoft.com/en-us/windows/wsl/install-win10
      • We recommend the Ubuntu Linux distribution, but any Linux distribution will have an SSH client

Use ssh (secure shell) to login to a remote computers.

# General form:
ssh <user_name>@<full_host_name>

# For example
ssh abattenh@ls6.tacc.utexas.edu

...

tail /etc/passwd | while IFS=':' read account x uid gid name shell
do 
  echo $account $name
done | more

Writing multiple text lines

There are several ways to output multi-line text. You can:

• Start the text with a single quote or a double quote
  • press Enter when you want to start a new line
  • keep entering text and Enter until you're satisfied
  • supply the matching single quote or a double quote then Enter

  • example:

    Code Block
    echo 'My name is Anna'

    
    

• Use echo -e
  
  • The -e option tells echo to replace some special backslash escapes characters that represent non-printable characters with their associated ASCII codes
    
    • So \n will be replaced by a newline (linefeed) character and \t will be replaced by a Tab.

  • example:

    Code Block
    echo -e "My\nname is\nAnna"

    
    

heredoc

Another method for writing multi-line text that can be useful for composing a large block of text in a script, is the heredoc syntax, where a block of text is specified between two user-supplied block delimiters, and that text block is sent to a command. The general form of a heredoc is:

COMMAND << DELIMITER
..text...
..text...
DELIMITER

For example, using the (arbitrary) delimiter EOF and the cat command:

cat << EOF
This text will be output
And this USER environment variable will be evaluated: $USER
EOF

Here the block of text provided to cat is just displayed on the Terminal. To write it to a file just use the 1> or > redirection syntax after the block delimiter you name:

cat << EOF 1> out.txt
This text will be output
And this USER environment variable will be evaluated: $USER
EOF

The out.txt file will then contain this text:

This text will be output
And this USER environment variable will be evaluated: student01

Copying files between TACC and your laptop

Anchor
Copying_files_to_from_TACC Copying_files_to_from_TACC

...