L ve the Terminal
Because life is better when you can
work on the command line
Mike West
Yahoo! Frontend Summit, Dec. 2007
Slides:
http://mikewest.org/file_download/12

The command line is complex, and
quite impossible to cover fully.
So let’s begin by limiting our scope.

What’s the good stuff?

Foundations
Unix-style systems all behave according to
similar rules; understanding those
underlying ideas and processes is critical.

Connectivity
My computer is a paperweight without a
network; I need to get secure access to
many remote machines, and do things there.

Scripting
Don’t type the same things over and over;
save your sanity with just a little
understanding of Bash aliases and functions.

Foundations
http://flickr.com/photos/johnseb/458716114/

Foundations
Unix-style systems are built
primarily on small, single-purpose
utilities that can be chained
together for larger effect.
http://flickr.com/photos/johnseb/458716114/

Foundations
Each of these tools operates in one
way or another on streams.
http://flickr.com/photos/johnseb/458716114/

Foundations
STDOUT
$> ls
file-1.txt file-2.txt
$>
http://flickr.com/photos/johnseb/458716114/

Foundations
STDIN
$> perl
$x = “Hello, world!”;
print \"\\n$x\\n\";
^D
Hello, world!
$>
http://flickr.com/photos/johnseb/458716114/

Foundations
STDERROR
$> perl
$x = 1/0; print \"\\n$x\\n\";
Illegal division by zero at - line 1.
$>
http://flickr.com/photos/johnseb/458716114/

Foundations
Stream Redirection
http://flickr.com/photos/johnseb/458716114/

Foundations
Input Redirection: `<`
mikewest:~/some_dir westm$ validator < ./tmp.html
mikewest:~/some_dir westm$
http://flickr.com/photos/johnseb/458716114/

Foundations
Output Redirection: `>` and `>>`
mikewest:~/some_dir westm$ ls > ./tmp
mikewest:~/some_dir westm$
http://flickr.com/photos/johnseb/458716114/

Foundations
Error Redirection: `2>`
mikewest:~/some_dir westm$ errorful 2> ./dev/null
mikewest:~/some_dir westm$ errorful > ./dev/null 2>&1
mikewest:~/some_dir westm$
http://flickr.com/photos/johnseb/458716114/

Foundations
Chaining Streams
http://flickr.com/photos/johnseb/458716114/

Foundations
Small Utilities, Working Together: `|`
$> ls -la | sort -r -k 5 | head -3
-rw-r--r-- 1 westm westm 34749 Oct 19 12:11
SiteAssistant.js
-rw-r--r-- 1 westm westm 12292 Oct 18 22:51 .DS_Store
-rw-r--r-- 1 westm westm 8161 Oct 19 11:35
SiteAssistant.css
Lists the 3 (`head`) largest (`sort`) files in the current directory (`ls`)
http://flickr.com/photos/johnseb/458716114/

Foundations
Permissions System
http://flickr.com/photos/johnseb/458716114/

Foundations
Each file has an “owner”, a “group”,
as well as 3 sets of execute, read,
and write permission bits.
http://flickr.com/photos/johnseb/458716114/

Foundations
$> ls -lah
-rw-r--r-- 1 westm westm 2K Aug 2 2001 xmalloc.c
$> chmod 777 xmalloc.c
$> ls -lah
-rwxrwxrwx 1 westm westm 2K Aug 2 2001 xmalloc.c
1 --x execute
2 -w- write
3 -wx write and execute
4 r-- read
5 r-x read and execute
6 rw- read and write
7 rwx read, write and execute
http://flickr.com/photos/johnseb/458716114/

Foundations
Process Control
http://flickr.com/photos/johnseb/458716114/

Foundations
You can start processes in the
background with `&`, pause
processes with Crtl-Z, and deal
with paused processes using `fg`
and `bg`.
http://flickr.com/photos/johnseb/458716114/

Foundations
Demo go her\"
http://flickr.com/photos/johnseb/458716114/

Foundations
Editing Files
http://flickr.com/photos/johnseb/458716114/

Foundations
Avoid holy wars; just use VIM.
http://flickr.com/photos/johnseb/458716114/

Foundations
Demo go her\"
http://flickr.com/photos/johnseb/458716114/

Connectivity
http://www.flickr.com/photos/hi-phi/36854889/

Connectivity
Whatever your connectivity needs,
SSH is almost certainly the answer.
http://www.flickr.com/photos/hi-phi/36854889/

Connectivity
Passwords are annoying
L
mikewest:~ westm$ ssh mikewest@mikewest.org
I
Password:
Last login: Thu Nov 29 11:45:59 2007 from 193.93.196.161
_____________________________________
A
________| |_________
\\ | girard.joyent.us | /
\\ | | /
F
\\ | \"Mrs. Robinson, you're trying | /
\\ | to seduce me. Aren't you?\" | /
/ |_____________________________________| \\
/___________) (___________\\
[girard:~] mikewest$
http://www.flickr.com/photos/hi-phi/36854889/

Connectivity
SSH Keys are much better
http://www.flickr.com/photos/hi-phi/36854889/

Connectivity
SSH Keys are much friendlier and
are trivial to create and use.
http://www.flickr.com/photos/hi-phi/36854889/

Connectivity
Just run `ssh-keygen`
mikewest:~ westm$ ssh-keygen -t rsa -b 2048
Generating public/private rsa key pair.
Enter file in which to save the key (/Users/westm/.ssh/
id_rsa): /Users/westm/.ssh/test_rsa
Enter passphrase (empty for no passphrase):
Enter same passphrase again:
Your identification has been saved in /Users/westm/.ssh/
test_rsa.
Your public key has been saved in /Users/westm/.ssh/
test_rsa.pub.
The key fingerprint is:
8f:0b:e7:ea:17:61:69:6a:11:06:f5:56:ac:70:c4:69
westm@mikewest.munich.corp.yahoo.com
http://www.flickr.com/photos/hi-phi/36854889/

Connectivity
Upload to the server, and append to
~/.ssh/authorized_keys
mikewest:~ westm$ scp /Users/westm/.ssh/test_rsa.pub \\
mikewest@mikewest.org:~/.ssh/authorized_keys
http://www.flickr.com/photos/hi-phi/36854889/

Connectivity
Of course, you will create
passphrased keys, because
anything else is idiocy.
http://www.flickr.com/photos/hi-phi/36854889/

Connectivity
SSH Agent
http://www.flickr.com/photos/hi-phi/36854889/

Connectivity
SSH Agent is Easy
mikewest:~ westm$ eval `ssh-agent`
Agent pid 80094
mikewest:~ westm$ ssh-add
Enter passphrase for /Users/westm/.ssh/id_rsa:
Identity added: /Users/westm/.ssh/id_rsa (/Users/
westm/.ssh/id_rsa)
mikewest:~ westm$
http://www.flickr.com/photos/hi-phi/36854889/

Connectivity
SSH Agent + Screen
http://www.flickr.com/photos/hi-phi/36854889/

Connectivity
Demo go her\"
http://www.flickr.com/photos/hi-phi/36854889/

Scripting
http://www.flickr.com/photos/mortimer/221051561/
http://www.flickr.com/photos/hi-phi/36854889/

Scripting
Elimination of mindless repetition
from your daily life is essential to
your continued sanity.
http://www.flickr.com/photos/mortimer/221051561/
http://www.flickr.com/photos/hi-phi/36854889/

Scripting
Uploading SSH Keys, for instance.
#!/bin/bash
KEY=\"$HOME/.ssh/id_rsa.pub\"
if [ -z $1 ];then
echo \"Usage: \\`upload_keys username@host\\`\"
else
echo \"Putting your key on $1... \"
ssh -q $1 <<- HEREDOC
umask 0077;
mkdir -p ~/.ssh;
echo \"`cat $KEY`\" >> ~/.ssh/authorized_keys
echo \"done!\"
HEREDOC
fi
http://www.flickr.com/photos/mortimer/221051561/
http://www.flickr.com/photos/hi-phi/36854889/

Scripting
Aliases
mikewest:~ westm$ ll
-/bin/bash: ll: command not found
mikewest:~ westm$ alias ll=’ls -lah’
mikewest:~ westm$ ll
< magically insert result of `ls -lah` here >
mikewest:~ westm$
http://www.flickr.com/photos/mortimer/221051561/
http://www.flickr.com/photos/hi-phi/36854889/

Scripting
Functions
mikewest:~ westm$ httpload() {
echo \"http://$1\" > /var/tmp/$1.http_load_temp_file
http_load -parallel $2 -seconds $3 /var/tmp/
$1.http_load_temp_file
rm -f /var/tmp/$1.http_load_temp_file
}
mikewest:~ westm$ httpload mikewest.org 1000 1000000
< magically insert my crashing, burning website here >
mikewest:~ westm$
http://www.flickr.com/photos/mortimer/221051561/
http://www.flickr.com/photos/hi-phi/36854889/

Scripting
You can put frequently used
functions or aliases into
`~/.bash_login` so they’re available
immediately.
http://www.flickr.com/photos/mortimer/221051561/
http://www.flickr.com/photos/hi-phi/36854889/

Questions?
Mike West
mike@mikewest.org
http://mikewest.org/