Files

printing to system output

print file line by line

cat [file]

print file line by line (reverse order)

tac [file]

multiple files

cat [file1] [file2] [file3] ...

echo stdin to output (essentially a noop)

echo [message] | cat -

insert output from stdin between file contents

echo middle | cat [file+] - [file+]

cat as a multiline echo

cat << EOF
important message
blabla
more blabla
EOF

Copy

copy file

cp original destination

copy directory

cp -r directory destination

copy don't overwrite (useful for backups)

cp -n original destination

Move

move file

mv original destination

move file (verbose)

mv -v [source] [destination]

Soft link

create soft link (general form)

ln -s [existing target] [link to create]

concrete example

ln -s ~/.bashrc /tmp/bashrc

create links to files with their original name in a destination directory

ln -s ~/.b* .

get the destination of a link on the filesystem

readlink [existing_link]

rsync

copy directory

rsync -r [from] [to]

copy directory contents only (because of slash)

rsync -r [from]/ [to]

copy directory verbose

rsync -rv [from] [to]

delete missing files in destination

rsync -r [from] [to] --delete

copy files from source/data to destination/data without overwriting

rsync -r --ignore-existing source/data destination

move files (not links) from source/data to destination/data without overwriting

rsync -r --ignore-existing --remove-source-files source/data destination

same as above, but create hardcopies of links

rsync -r --ignore-existing --remove-source-files --copy-links source/data destination

unison (rsync alternative)

copy directory

unison -auto -batch [from] [to]

duplicate files

find duplicate files in a directory

fdupes [directory]

search nested directories also

fdupes -r [directory]

ask which duplicate files to delete

fdupes -d [directory]

auto delete all but first

fdupes -N [directory]

split a file into chunks

split a file into chunks of specified size

split --bytes 500M --numeric-suffixes --suffix-length=3 [input] [output file prefix]

line endings

the file command will report it when a file has CRLF line terminators (dos line endings)

file [file]

replace DOS style line endings with UNIX style line endings

dos2unix [file]...

replace UNIX style line endings with DOS style line endings

unix2dos [file]...