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Linux/Unix

Compressing files (tar)​

Resource: https://angular.io/cli/generate#component

tar -cvf documents.tar /home/jmm/documents/ Create a tar file

  • -cvf = compress, verbose (list files), filename (to be compressed into)
  • documents.tar = the output file containing files
  • /home/jmm/documents/ = input directory or file

tar -xvf documents.tar -C /home/jmm/new-documents/ Extract from a tar file

  • -xvf = eXtract, verbose (list files), filename (to extract from)
  • documents.tar = .tar file to extract from
  • -C = directory to extract into

SSH​

Resource: https://linux.die.net/man/1/ssh

ssh jmm@192.168.1.123 SSH into server at 192.168.1.123 as user "jmm" (will be asked for password if ssh keys not setup)

ssh jmm@192.168.1.123 ls Run the ls command on the server at 192.168.1.123 and show results of command in local machine terminal

SCP​

Resource: https://linux.die.net/man/1/scp

scp pi@192.168.1.123:/home/jmm/.bashrc /home/jmm/ use SCP to copy .bashrc file from server at 192.168.1.123 to local machine /home/jmm/ directory

scp /home/jmm/.bashrc pi@192.168.1.123:/home/jmm/ use SCP to copy .bashrc file from local machine to server at 192.168.1.123

GREP​

Resources:

grep Docker ./readme.md search for all lines that contain "Docker" in the readme.md file

grep -r --exclude-dir=node_modules Docker search for all lines that contain "Docker" recursively excluding the node_modules directory

grep -r --exclude=*.{png,jpg} Docker search for "Docker" recursively and exclude files of type .png and .jpg

grep -Irn Docker recursively search for "Docker" while excluding binary files and return the line number

-I -- process a binary file as if it did not contain matching data;
-n -- prefix each line of output with the 1-based line number within its input file
-i -- case insensitive search

CURL​

curl https://www.website.com/file.pdf --output file.pdf Download the file at the web address specified and save to an output file

curl -k https://www.website.com/file.pdf --output file.pdf allow insecure/self-signed-cert

Network​

lsof -i -P -n | grep LISTEN Check open ports

Command History Tricks​

View recent commands​

history - view recent commands

history | grep -i "cargo" - view recent commands in history that include "cargo", -i is case-insensitive

!dotnet:p - display the most recent command that started with "dotnet"

!12:p - display the command at index 12

Rerun recent commands​

CTRL + p - paste in the most recent command that you ran, need to hit enter to run

!! - immediately rerun last command

!dotnet - immediately rerun last command that started with "dotnet"

!12 - immediately rerun command at index 12

Misc​

diff <(ls old) <(ls new) diff the output of two commands (such as comparing the contents of two directories)

echo -n "string to encode here" | base64 -w 0 base64 encode a string. -n removes the newline character when echoing, -w 0 prevents auto wrapping lines (default is 76 chars, base64 --help for more info)

printf '%-32s' "Here is text!" >> /dev/ttyS3 print a string padded with spaces to 32char and send to serial device

Read in a secret value (such as a password) from the command line so that it doesn't appear in shell history:

#!/bin/sh
echo -n "Enter secret: "   # echo text with no newline
read -s secret             # read in secret without showing chars
echo $secret               # do something with secret value (defo don't echo it)