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Contents 1 Convert .avi video files to smaller .mp4 format 2 Convert GIFs from Twitter that download as MP4s back into uploadable GIFs again 3 Convert man page to text file 4 Convert RPM package to DEB package 5 Convert text files from MS-DOS format to UNIX format 6 Convert WordStar files to plain text 7 Copy a file 8 Create a custom command to list files 9 Create a directory using today's date 10 Create a file and a directory with unique names from the system clock 11 Create a link 12 Remove empty directories under the working directory 13 Display all subdirectories in a tree format 14 Display time since boot 15 Display unique lines in a sorted file 16 Download streaming videos and convert them to MP3s 17 Extract audio from any video file 18 Extract gzip compressed tar archives 19 Extract pages from a PDF to build a new PDF 20 Extract tarball 21 Find duplicates on your filesystem 22 Find files by name 23 Find man page for a command 24 Find ten biggest hogs of disk space under a directory 25 Find text in a file 26 Format floppy disk 27 Generate a pdf from a man page 28 Generate a random password 29 Get a weather forecast for your city 30 Get information about all files of a certain type 31 Get the sizes of all subdirectories under a directory 32 Get your public IP address 33 Grab a copy of a website 34 List primes between 2 and any number 35 List the misspelled words in a file 36 Make a file executable for all users 37 Make a file lowercase 38 Make all filenames in a directory lowercase 39 Make a new file of the individual words in another file 40 Make an image of a CD on your hard drive 41 Make archive 42 Make directories for 36 months using brace expansion: 43 Make ISO from temp directory 44 Make the ls command print in a tree format 45 Make the ls command useful for a change 46 Make the text in a file all uppercase 47 Mount that image on your system to use it 48 Mount your SquashFS file 49 Move all files starting with "B" into the b subdirectory 50 Move all the .jpg images from one folder to another folder, recursively 51 MP3 to WAV conversion 52 Perform a ROT 13 conversion 53 Prime factors of first 100 integers 54 Print a complete date-time group 55 Print the current month in Julian dates 56 Recursively move mp3 files in many directories to a single target directory 57 Rename all files with extension .OUT with the extension .txt 58 Rename in bulk 59 Replace spaces in a filename with hyphens 60 Replace spaces in the filename of all the files in a directory with hyphens 61 Return pi to the number of digits specified on the command line (Answer grows more accurate the longer the fractional part) 62 Return the name of the most-recently modified file in a directory 63 Run the last command again as root 64 Send a man page to the terminal minus the embedded backspace characters 65 Tally up a column of figures 66 Turn a directory into a SquashFS file 67 Turn the capslock key into a second ESC key 68 Upload a file to your webspace 69 Use imagemagick to take a screen shot 70 Use CUPS printer management system 71 Use the command line as a quick calculator

Convert .avi video files to smaller .mp4 format

ffmpeg -i 'U2 - New Years Day.avi' 'U2 - New Years Day.mp4'

Convert GIFs from Twitter that download as MP4s back into uploadable GIFs again

ffmpeg -y -i input.mp4 -filter_complex "scale=320:-1:flags=lanczos[x];[x]split[x1][x2]; [x1]palettegen[p];[x2][p]paletteuse" output.gif

Convert man page to text file

man concalc | col -bx >concalc.txt

Convert RPM package to DEB package

alien file.rpm

Convert text files from MS-DOS format to UNIX format

tr -d '\r' <MULE.ASC >mule.txt

Convert WordStar files to plain text

cat rubymae.ws | tr -c '[:print:]\t\r\n' '[ *]' >rubymae.txt

Copy a file

cp INFILE OUTFILE

Create a custom command to list files

alias l = 'ls -l --color=auto'

Create a directory using today's date

mkdir $(date +%Y%m%d)

Create a file and a directory with unique names from the system clock

touch "$(date +"%y%m%d%H%M%S")";sleep 1; mkdir "$(date +"%y%m%d%H%M%S")"

Create a link

ln -s /initrd/mnt/dev_ro2 HOME

Remove empty directories under the working directory

find . -empty -exec rm -rf {} \;

Display all subdirectories in a tree format

ls -R | grep ":$" | sed -e 's/:$//' -e 's/[^-][^\/]*\//----/g' -e 's/^//' -e 's/-/|/'

Display time since boot

uptime

Display unique lines in a sorted file

uniq <FILE1 >FILE2

Download streaming videos and convert them to MP3s

sudo curl -L https://yt-dl.org/downloads/latest/youtube-dl -o /usr/local/bin/youtube-dl sudo chmod a+x /usr/local/bin/youtube-dl youtube-dl --title --extract-audio --audio-format mp3 https://www.youtube.com/watch?v=L3FmBjX-p0I

Extract audio from any video file

ffmpeg -i Pet-Shop-Boys---West-End-Girls.mp4 -vn west-end-girls.ogg

Extract gzip compressed tar archives

gunzip progs.tar.gz tar xvf progs.tar

Extract pages from a PDF to build a new PDF

ps2pdf -dFirstPage=4 -dLastPage=8 input.pdf output.pdf

Extract tarball

tar -xvf /dev/hda/FILE

Find duplicates on your filesystem

duff -r *

Find files by name

find . -name *wav -print

Find man page for a command

whereis -m genisoimage genisoimage: /usr/share/man/man1/genisoimage.1.gz

Find ten biggest hogs of disk space under a directory

du -s /usr/share/* | sort -nr | head

Find text in a file

awk 'chevy' cars.txt

Format floppy disk

fdformat /dev/sde

Generate a pdf from a man page

man -t vim | ps2pdf - > vim.pdf

Generate a random password

openssl rand -base64 12

FRYSkfIikVA7AuNm

openssl rand -base64 24

l8Ht0b83wCAnH95izexZStOW73IqH/Mz

Get a weather forecast for your city

curl wttr.in/seattle

Get information about all files of a certain type

find . -name *com -exec file {} \;

Get the sizes of all subdirectories under a directory

du -sh MYDIR

Get your public IP address

curl ifconfig.me; echo

Grab a copy of a website

wget -w9 -r --random-wait -l3 -np -E https://rosettacode.org/wiki/Rosetta_Code

List primes between 2 and any number

#!/bin/bash
for (( i=2; i<=$1; i++ ));do
l=$(factor $i | cut -d : -f 1)
r=$(factor $i | cut -d : -f 2 | sed 's/ //g')
if (( $l == $r ));then
echo $i
fi
done

List the misspelled words in a file

enchant -l matthew

Make a file executable for all users

chmod u+x FILE

Make a file lowercase

cat FILE1.TXT | tr '[A-Z]' '[a-z]' > FILE2.TXT

Make all filenames in a directory lowercase

#!/bin/bash 
for x in `ls` 
do 
if [ ! -f $x ]; then 
continue 
fi 
lc=`echo $x | tr '[A-Z]' '[a-z]'` 
if [ $lc != $x ]; then 
mv -i $x $lc 
fi 
done 

paste into file called lowerit chmod u+x lowerit ./lowerit

Make a new file of the individual words in another file

tr ' ' '\012' <INFILE >OUTFILE

or

for WORD in `cat FILE`
do
echo $WORD
done

Make an image of a CD on your hard drive

dd if=/dev/sr0 of=image.iso

Make archive

tar -c DIRECTORY | bzip2 > DIR.TAR.BZ2

Make directories for 36 months using brace expansion:

mkdir {2021..2023}-{01..12}

Make ISO from temp directory

genisoimage -r -joliet-long -o files1.iso temp

Make the ls command print in a tree format

alias tree="ls -R | grep ":$" | sed -e 's/:$//' -e 's/[^-][^\/]*\//--/g' -e 's/^//' -e 's/-/|/'"

Make the ls command useful for a change

alias ls='ls -lhGpt --color=always'

Make the text in a file all uppercase

cat testa.txt | tr '[a-z]' '[A-Z]' > testb.txt

Mount that image on your system to use it

(The mount point must already exist) mount -o loop image.iso /mnt/temp

Mount your SquashFS file

mount -o loop -t squashfs PUP_412.SFS /mnt/pup

Move all files starting with "B" into the b subdirectory

find -name "B*.*" -exec mv {} b \;

Move all the .jpg images from one folder to another folder, recursively

find www.cleanposts.com -type f -name *.jpg -exec mv '{}' /home/teresita/Downloads \;

MP3 to WAV conversion

madplay --output=wave:OCEANLAB.WAV OCEANLAB.MP3

Perform a ROT 13 conversion

#!/bin/sh
echo "$1" | tr '[A-Za-z]' '[N-ZA-Mn-za-m]'

Prime factors of first 100 integers

echo {1..100} | factor

Print a complete date-time group

date '+%Y-%m-%d/%k:%M:%S'

Print the current month in Julian dates

cal -j

Recursively move mp3 files in many directories to a single target directory

find -name '*.mp3' -exec mv -i {} /home/minix/Desktop/music \;

Rename all files with extension .OUT with the extension .txt

rename 's/\.OUT$/.txt/' *

Rename in bulk

OLD=xxx
NEW=yyy
for F in $OLD*
do
SUFFIX=`expr $F : '$OLD\(.*\)'`
mv $OLD$SUFFIX $NEW$SUFFIX
done

Replace spaces in a filename with hyphens

find . -name "* *mp3" -exec rename 's/\ /-/g' {} \;

Replace spaces in the filename of all the files in a directory with hyphens

find . -name "* *mp3" -exec rename 's/\ /-/g' {} \;

Return pi to the number of digits specified on the command line (Answer grows more accurate the longer the fractional part)

#!/bin/bash 
echo "scale=$1;a(1)*4" | bc -l

Return the name of the most-recently modified file in a directory

$ ls -t | head -1

Run the last command again as root

sudo !!

Send a man page to the terminal minus the embedded backspace characters

man genisoimage | col -b | less

Tally up a column of figures

#! /bin/sh
case "$1" in 
[1-9]*) colnum="$1"; shift;; 
*) echo "Usage: `basename $0` colnum [files]" 1>&2; exit 1;; 
esac 
awk '{sum += $col} 
END {print sum}' col=$colnum OFMT='%.2f' ${1+"$@"}

Turn a directory into a SquashFS file

mksquashfs /tmp/merge PUP_412.SFS

Turn the capslock key into a second ESC key

setxkbmap -option caps:escape

Upload a file to your webspace

wput MYFILE ftp://username:password@web.host.com

Use imagemagick to take a screen shot

import screenshot.jpg

Use CUPS printer management system

localhost:631 (in a browser address bar)

Use the command line as a quick calculator

echo $((145+5))
echo $((145-5))
echo $((145*5))
echo $((145/5))
echo $((145%5))
echo $((145**5))