Resize an image from command line

convert -resize 50% original.png resized.jpg

convert is part of the ImageMagick package.

List files and exclude directories

find . -name '*.js' ! -path '*/vendor/*'

git grep -l 'pattern' | xargs sed -i 's/pattern/relacement/g'

paste -s -d':'

Useful when the output of one command in on multiple lines, and a single line is wanted.

(Without having to count its index)

grep 'pattern' | rev | cut -d'/' -f 1 | rev

Uses the rev command to reverse all characters, select the first field, then reverse again.

$!!

To repeat the previous command but replace the first occurence of "foo" with "bar":

$ !!:s/foo/bar

For a global substitution:

$ !!:gs/foo/bar

See Event designators in man bash.

mv supports a --backup option to rename the source file if a destination of the same name exists.

Example with the tree below:

src/
|__ bar
|__ foo

dest/
|__ foo

Running:

# use 'numbered' backup
$ mv --backup=t src/* dest/

results in:

src/

dest/
|__ bar
|__ foo
|__ foo.~1~ # original dest/foo

!!:s/foo/bar