Basics Flashcards
Essential commnds
get the HTTP headers for https://foo.com
curl -I foo.com
get the HTML for foo.com and follow any redirects
curl -L foo.com
create a udp connection listening on 127.0.0.1 port 3333
nc -luv 127.0.0.1 -p 3333
create a udp connection to 127.0.0.1 on port 3333 in order to send/receive raw data
nc -uv 127.0.0.1 3333
scan ports 100-200 on localhost and return the available services
nmap -sV -p 100-200 127.0.0.1
open an ssl connection to localhost port 12345
openssl s_client -connect localhost:12345
securely upload file foo.txt to remote location bar.com/fubar as user foo
rsync -chavez ssh foo.txt foo@bar.com/fubar/
securely download file from location bar.com/fubar/foo.txt to directory “fubar”
rsync -chavez ssh foo@bar.com/fubar/foo.txt /fubar
SSH in as “foo” into “bar.com” on port 2222 using key fubar.sshkey
ssh foo@bar.com -i fubar.sshkey
SSH in as “foo” into “bar.com” on port 2222
ssh foo@bar.com -p 2222
SSH in as “foo” into “bar.com” on port 2222 disabling the pseudo-terminal
ssh foo@bar.com -p 2222 -T
SSH add key named “foo” to auto login
ssh-add foo
SSH create a ssh key pair
ssh-keygen -t rsa -b 4096
display free disk space in human readable format
df -h
environment
env
help for foo
foo -help
show group memberships
groups
manual for foo
man foo
present working directory
pwd
show system & kernel
uname -a
who is logged in
w
show effective user id
whoami
list directory contents
ls
List directory content one entry per line
ls -1
List directory content in long format
ls -l
List directory content display all
ls -la
List directory content long format sorted by size
ls -lS
List directory content long format sorted newest first
ls -lt
List directory content comma format
ls -m
List directory content with directories ending in trailing slash
ls -p
List directory content recursively
ls -R
List directory content in reverse order
ls -r
run an executable named “fubar” in the current directory
./fubar
decode a text file named “fubar.txt” using Base64
base64 -d fubar.txt
decompress bzipped file named fubar.bz2
bzip2 -d fubar.bz2
output the contents of a file named “-fubar” in current directory
cat ./-fubar
output a file named “foo bar.txt”
cat ‘foo bar.txt’
output the list of valid shells on current system
cat /etc/shells
output the contents of a user’s shell script named “fubar”
cat /usr/bin/fubar
concatenate/print file foo.txt
cat foo.txt
output unique lines in file named “foo.txt”
cat foo.txt | sort | uniq -u
change directory up a level
cd ..
go to directory “foo” and list all files
cd foo && ls -la
copy recursively from foo into bar dir
cp -R foo bar
copy all txt files into foo dir
cp *.txt foo
make a copy file foo named bar
cp foo bar
find the difference between two files “foo” and “bar”
diff foo bar
identify what kind of file “fubar” is
file fubar
decompress gzipped file fubar.gz
gzip -d fubar.gz
show first lines of a file foo.txt
head foo.txt
scroll through foo.txt
less foo.txt
make directory tree foo/y/z
mkdir -p foo/y/z
make directory foo
mkdir foo
move/rename file foo.txt to my/bar.txt
mv foo.txt my/bar.txt
remove directory “foo” recursively
rm -R foo
remove file foo.txt
rm foo.txt
show the last part of a file foo.txt in real time
tail -f foo.txt
show the last part of a file foo.txt
tail foo.txt
create zipped file archive from foo
tar czf foo.tar.gz foo
extract zipped file archive named bar.tar.gz
tar xzf foo.tar.gz
create file foo.txt
touch foo.txt
reverse a hexdump of “foo” back to its original format named “bar”
xxd -r foo > bar
read the contents of foo.txt and output it to bar.txt
cat < foo.txt > bar.txt
read the contents of foo.txt and append it to bar.txt
cat < foo.txt»_space; bar.txt
read file foo.txt, sort it and remove duplicates
cat foo.txt | sort | uniq
read file foo.txt, sort it, remove duplicates and output to
cat foo.txt | sort | uniq | tee bar.txt
change dir to fubar, else list current directory in long format
cd fubar || ls -l
clear the screen, and if successful, list contents of direct
clear && ls
write foo to standard output
echo foo
list the contents of fubar and append all output to result
ls fubar &» results.txt
list the contents of nonexistent fubar and append the stan
ls fubar 2» errors.txt
search a csv file named bar.txt for “foo” and print value of first column
awk ‘/foo/ {print $1}’ bar.csv
find file with filesize of 1033 bytes
find . -size 1033c
find any php files, case insensitive
find ./ -iname “*.php”
find file with user “foo”+group “bar”+size 33bytes, and throw away errors
find / -user foo -group bar -size 33c 2>/dev/null
search recursively, case-insensitive for string foo in all
grep -Ri “foo” *
search recursively, case-insensitive, word “foo” in all text files
grep -Riw “foo” *.txt
or use: awk ‘/millionth/ {print $2}’ data.txt
grep “foo” bar.txt
lookup which shell user “fubar” is running
grep fubar /etc/passwd
find file foo.txt using cache db
locate foo.txt
search & replace “foo” with “bar” in file fubar.txt
sed ‘s/foo/bar/’ fubar.txt
output printable text at least 11 characters long from file “fubar.txt”
strings -11 fubar.txt
Encode/decode a file named “foo.txt” using ROT13
tr ‘A-Za-z’ ‘N-ZA-Mn-za-m’ < foo.txt
give group and others only permision to read dir “foo”
chmod -R go=r foo
give user full rights on dir “foo”
chmod -R u=rwx foo
make script “foo.sh” executable for everyone
chmod +x foo.sh
change owner to foo and group to bar recursively on fubar di
chown -R foo:bar fubar
switch user to foo
su foo
execute foo as another user
sudo foo
kill process 123 dead in its tracks
kill -9 123
kill all processes named foo dead in their tracks
killall -9 foo
display process status
ps
pause current process for 11 seconds
sleep 11
display sorted info on processes
top
In Vim, open a file name “fubar.txt”
:e fubar.txt
In Vim, set the shell to bash
:set shell=/bin/bash
In Vim, start a shell
:shell
After opening a file in Less or More, switch to Vim editor
v
cut line
CTRL-k
output to copy
CTRL-o
read
CTRL-r
paste line
CTRL-u
close
CTRL-x
edit file foo in nano
nano foo
Clone a git repo using ssh and save it as “fubar”
git clone ssh://[user@]host.xz[:port]/path/to/repo.git/ fubar
In Git, commit a file named “fubar”
git commit -m “Message goes here” fubar
In Git, push commited changes to master
git push
In Git, search a repo for the string “password”
git rev-list –all | xargs git grep -F ‘password’
In Git, show the contents of tag named “foo”
git show foo
In Git, stage a file named “fubar”, bypassing .gitignore
git stage -f fubar
In Git, show all tags in current repo
git tag
immediately rerun the previous command
!!
go to start of line
CTRL-a
cancel current command
CTRL-c
got end of line
CTRL-e
search history of previous commands
CTRL-r
sleep current program
CTRL-z
display history of previous commands
history
display previous command
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