Command line fun
export (setting a variable)
export b=10.11.1.220
Instead of typing things over and over, you can just assign variables.
after assigning, you can just do a dollar sign $b
var="My Var"
echo $var
this assigning method only works during the current session. If you create another bash session, it won't work.
There are default environmental variables in Kali Linux. You can view them by typing: env
Bash History Tricks (use the commands you used previously!)
type: history
then type, for example, !262 to call the command with the desgnated number assigned.
$HISTSIZE
$HISTFILESIZE
these variables control command history and can be changed .
command history search with CTR+R!
saving output to a file
echo "test" > redirection_test.txt
if you output something to an existing file, the content will be replaced. (no undo!)
echo "this is added! " >> redirection_test.txt
> will add a sentence after and not overwrite.
Redirect from a file:
wc -m < redirection_test.text
(counts word count)
**STDERR (0, 1 or 2) **
**2 = standard error? **
If you don't want certain standard errors to show in the terminal, type:
**2>/dev/null inside the command. **
**You can also redirect errors to a file: 2>output.txt **
Piping - use more than one command in one line.
Test searching
Grep
i.e) ls -la /usr/bin | grep zip
sed
echo "I need to try hard" | sed 's/hard/harder/"
output > I need to try harder
replacing hard with harder.
Cut
cut -f (specifying a field)
cut -d (delimiter)
i.e) echo "I'm from Kasama, Ibaraki, Japan." | cut -f 2 -d ","
output > Ibaraki
awk
data extracting
awk -f (field seperater)
echo "hello::there::friend" | awk -F "::" '{print $1, $3}'
output > hello friend
**cut can only use one separator but awk is much more flexible. **
head command shows the first 10 lines of a file.
uniq -c (shows the number of occurances)
sort -urn
-u unique
-r descending order
-n numerical order
Editing Files from command line
1. Nano
ctr+K cut line
ctr+U paste
ctr+W search within the file
ctr+X exit
2. VI
Extremely fast
File Comparison
-COMM
compare two files
comm scan-a.txt scan-b.txt
-DIFF
much more complex and supports more output formats
diff -c scan-a.txt scan-b.txt
diff -u (unified format) cleaner and shorter
-vimdiff (highlights)
ctr+w
] + C - jumps to the next change
[ + C - to the previous one
D + O change from the other window to the current one
D + P opposite of the DO
Background processes
ping -c 400 localhost < ping_results.txt **& **
or run a command and suspend it with ctr+Z and then bg it
Jobs control
jobs command show what jobs are running in the current terminal session
fg %1 (foreground the session)
Process control with PS (system-wide)
ps -ef (e selects all processes and f is full-formatting)
ps -fC leafpad (finds leafpad process)
kill command kills processes (needs PID)
TTY- The name of the controlling terminal for the process.TIME- The cumulative CPU time of the process, shown in minutes and seconds.CMD- The name of the command that was used to start the process.
ps aux
a -- all users
u- user oriented format
x - shows processes that are running in the background
File and command monitoring
Tail command
sudo tail -f /var/log/apache2/access.log
(continuously updates the logs)
Watch command (runs commands every n second)
watch -n 5 w
---> w command lists logged in user
Downloading files
wget - downloads files using HTTP and FTP
wget -O report.pdf https://www.gorigorisensei.com/reoirts/pentest_reports.pdf
research more on this!
CURL
curl -o report.pdf http://www~~~
AXEL -a -n 20 -o
good for large downloads
Bash history customization
export HISTCONTROL=ignoredups
export HISTIGNORE="&:ls:[bf]g:exit:history:clear"
(setting these variables will ignore duplicate commands and specified frequently used/meaningless commands"
HISTTIMEFORMAT='%F %T ' - setting different time formatting for history
ALIAS - shorter commands that we can customize
alias lsa='ls -la'
customization of bash
by editing .bashrc file we can set persistent alias commands.
type: less .bashrc to see the file.
Exercises: finding files that have been updated in last 7days
find -type file -mtime -7
-mtime days
-mmin minutes
Use a combination of watch and ps to monitor the most CPU-intensive processes on your
Kali machine in a terminal window; launch different applications to see how the list changes
in real time.
watch -n 1 ps -aux --sort=-%cpu
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