Deprecated. See: https://github.com/gregelin/DataScienceLab4Lawyers
| You type the command: | Computer will: |
|---|---|
ls, ls -alh |
list files in current directory |
pwd |
show name of present working directory |
cd <directory> |
change directory to specified directory |
mkdir <directory> |
make directory empty <directory> |
rmdir <directory> |
remove directory empty <directory> |
cat <file> |
catentate <file> to output (print) |
more <file> |
show more of <file> with space key |
less <file> |
show less at a time <file> with arrow keys |
head -n 20 <file> |
head 20 lines of <file> |
tail -n 20 <file> |
tail 20 lines of <file> |
wc -l <file> |
word count lines in <file> |
cp <file1> <file2> |
copy <file1> to <file2> |
mv <file1> <file2> |
move <file1> to <file2> |
grep <pattern> <file> |
match global regular expression print <pattern> in <file> |
wget <url> |
web get <url> |
wget --no-check-certificate <url> |
web get <url> from https (some risk) |
awk -F "," '{ print $2 }' <file> |
Aho, Weinberger, and Kernighan's line filter to get second field of comma-delimited csv <file> |
also see:
| Key/combo: | Computer will: | Because: |
|---|---|---|
tab |
autocomplete filename | nobody remembers file names |
up arrow |
navigate back in command history | nobody remembers command syntax |
down arrow |
navigate forward in command history | nobody up arrows slowly |
delete |
delete character left | nobody types it right the first time |
left arrow |
move cursor left | nobody types it right the second time |
right arrow |
move cursor right | few type it right the third time |
ctrl+a |
jump to start of line | right file but wrong command |
ctl+e |
jump to end of line | there's always a fourth time |
ctl+c |
break process; stop | wtf? |
Like water through pipes, output from command can be input to next command.
# syntax for piping commands
command1 <file> | command2
# how many files in directory?
ls /etc/ | wc -l
# page through directory list
ls -alh /etc/ | more
# which flowers are about love?
cat /usr/share/misc/flowers | grep love
# which flowers are about love and are red?
cat /usr/share/misc/flowers | grep love | grep red
# split rows on ":" and print first "field" of row
awk -F ":" '{ print $1 }' /usr/share/misc/flowers
# split rows on ":" and print first "field"...
# then split output by "," and print first "field" of that
awk -F ":" '{ print $1 }' /usr/share/misc/flowers | awk -F "," '{ print $1 }'
# split rows on ":" and get first "field"...
# split that by "," and get first "field"...
# sort, uniqu counts, and sort alphanumerically
awk -F ":" '{ print $1 }' /usr/share/misc/flowers | awk -F "," '{ print $1 }' | sort | uniq -c | sort -n
syntax: ssh <username>@<servername>
example:
ssh ubuntu@ec2-54-197-147-122.compute-1.amazonaws.com
The authenticity of host 'ec2-54-197-147-122.compute-1.amazonaws.com (54.197.147.122)' can't be established.
RSA key fingerprint is e2:87:c2:1e:e3:09:ec:a0:a1:53:aa:a6:b3:fa:4a:c5.
Are you sure you want to continue connecting (yes/no)? yes
Warning: Permanently added 'ec2-54-197-147-122.compute-1.amazonaws.com,54.197.147.122' (RSA) to the list of known hosts.
ubuntu@ec2-54-197-147-122.compute-1.amazonaws.com's password:
Welcome to Ubuntu 12.04.2 LTS (GNU/Linux 3.2.0-41-virtual x86_64)