Robb. Knight.

I use iTerm with ZSH and Oh My Zsh. My dotfiles are available on Github.

Make Directory

mkdir directory_name

Move File

mv myfile.txt new_location/myfile.txt

# Use move to rename a file in place
mv old_name.txt new_name.txt

View Contents of File

cat myfile.txt

Write to File

# Overwrite existing contents
echo "Some content" > myfile.txt

# Append to content
echo "Some content" >> myfile.txt

# prepend to content
echo -e "Some Content\n$(cat myfile.txt)" > myfile.txt 

Diff Two Files

diff file1.txt file2.txt

# open in VSCode
diff file1.txt file2.txt | code -

# open in Sublime Text
diff file1.txt file2.txt | sublime -n

Batch Image Resize

Using sips (scriptable image processing system):

$ sips -Z 640 *.jpg

Invert Image Colours

for FILE in *; do convert $FILE -channel RGB -negate $FILE; done

QuickLook a File

qlmanage -p myfile.txt

Output to Variable

VARIABLE=$(pwd)

Show Calendar

$ cal
$ cal -y 2021

Variable is null

if [ -z "$VAR" ]; then
    echo "VAR is null"
    exit
fi

Output file list

for file in ./dir/*; do
    echo "${file##*/}"
done

touch ~/.hushlogin - Hide login message SSH to Ubuntu

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