useful-otw-bash-cmds

useful cmds / scripts

Bash Code

How to loop over all files in a directory and `cat` their contents to the stdout

# Get the pwd
> pwd
> /home/bandit4/inhere

# Set the file paths
> FILES=/home/bandit4/inhere/-file*

# Iterate over the files looking for the plaintext pwd
> for f in $FILES; do echo "Cating file $f"; cat $f; done

find

Check that a file is x size, text readable, and whether it is executable or not

> find . -type f -size 1033c ! -executable -exec sh -c 'file -b $0 | grep -q text' {}\; -print

find looks in the current directory for all files of type 'f' with size equal to 1033 bytes (c suffix) and that are not executable, then run the exec command to see what type of file it is (text or not).

find file by size, owner, and group owners

find / -size 33c -type f -user bandit7 -o -group bandit6

find line with word

find / -name "the-word-to-be-found" name-of-file.txt

sort

to find unique line

sort data.txt | uniq -u

grep

Regex search file

cat file.ending | format | grep '[^character]*$'

where ^ is the start of the line, * however many times, and $ means end of line.

base64

Test whether data is base64 or not

cat name-of-file.extension-tipe | grep -E '[A-Za-z0-9+/]{4}*([A-Za-z0-9+/]{4}|[A-Za-z0-9+/]{3}=|[A-Za-z0-9+/]{2}==)'

If true and have base64 tool

If the data is suspected to be encoded in base64 and there is the tool base64 installed then to decode it do: bas64 -d -i name-of-file.extension_type

where -d is to decode and -i is to ignore garbage such as newlines.

tr

For translation or deleting of characters.

rot13

cat datat.txt | tr 'A-Za-z' 'N-ZA-Mn-za-m'

Uncompressing Data Algorithm


# revert the data from hexdump
> cat name-of-data.extension_type | xxd -r name-of-data.extension_type > name-of-reverted-hexdump.file_ext

# find the compression algorithm used 
> file name-of-reverted-hexdump.file_ext

# w/e the type of algorithm used then rename file to match the same ending
> mv name-of-reverted-hexdump.file_ext data2.gz 

# uncompress it
> gzip -d data2.gz

# file to check

> file data2

# iterate through until all compression is gone and left with a plain ASCII file.

SSH

if you have the private key then you can use it to authenticate on a machine that has the public key.

Initiate a secure connection to a server

> openssl s_client -connect nameOfServer:portNumber

Can't create file?

If user cannot create file in location then create /tmp/location then change into the directory and create a file as normal.

Diff

Find the lines changed between two files

> diff file_1 file_2

Issue Command to a Server while connecting

ssh server@server.org -p num "cat ~/file.name"

setuid

If cannot run command then try changing the user 'id' so that user is allowed...

suconnect

How to set up a local server on a machine. Can do UDP or TCP connections as a server.

> nc -l localhost -p portNumber

md5sum

Useful for generating hashes from the terminal

Peter-Lankton/useful-otw-bash-cmds