Cheat Sheet :: Linux Shell Tricks

Date: 2020-06-16

Last Modified: 2026-02-01

Reading Time: 2 mins

To find the corresponding hex code

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echo -n "&" | hexdump -C

Command	Description/Purpose
command 2>filename	Redirect stderr to filename
command >output 2>filename	Redirect stderr to file named filename and stdout to file named output
command &> filename	Redirect stderr and stdout to filename
command 2>&-	Just suppress error messages. No file created. No error message displayed on screen
command 2>/dev/null	Just suppress error messages.
command 2>&1	Redirect error messages to standard output. Useful in shell script when you need to forcefully display error messages on screen

Note that we cannot just type the accent ^, instead we must use CTRL+V and then type CTRL+M.

If you want to remove blank lines (using vi): :g/^$/d
For commented lines (using vi): :g/^#/d
For lines where windows editor put ^M and you want to remove (using vi). :%s/^V^M//g
The final command will look like this: :%s/^M//g

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sed -e "s/^M//" file-orig.sh > file-mod.sh

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dos2unix input
dos2unix -b input

To delete a CRLF:

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tr -d '\r' < input > output

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egrep -v "^#|^$" squid.original > squid.conf

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grep -v ^["#"] squid.original > squid.conf

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rlwrap nc -nlv 443
rlwrap ./exploit.sh

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python -c 'import pty;pty.spawn("/bin/bash")'

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/usr/bin/python3 -c 'import pty;pty.spawn("/bin/bash")'

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stty raw -echo

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getfacl -Rp /home/psylinux/Desktop > /home/psylinux/permissoes_desktop.txt

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setfacl --restore=/home/psylinux/permissoes_desktop.txt -R

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apt install stow

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stow -v -t Target Folder1 Folder2 Folder3

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stow -v -D -t Target Folder1 Folder2 Folder3

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stow -v -R -t Target Folder1 Folder2 Folder3 Folder4

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stow -v -R -t Target Folder1 --ignore='SubFolder1' --ignore='SubFolder2'

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stow -v -R -t Target Folder1 --ignore='(?:\..*|[^+]*\+[^+]*)'