====== Files ======

File Types
  $ ls -l # shows type in the first character of the file permissions column
  
  where type is:
    * - : regular file
    * d : directory
    * c : character device file
    * b : block device file
    * s : local socket file
    * p : named pipe
    * l : symbolic link

  $ ls -F # appends symbols to filenames
  
  where symbol is:
    * @ : symbolic link (or that the file has extended attributes)
    * * : executable
    * = : socket 
    * | : named pipe
    * > : door
    * / : directory

Soft link
  $ ln -s filename linkname
  $ ln -s /media/john/Seagate\ Expansion\ Drive/ /seagate
  $ unlink /seagate

filename wildcards
  $ rm *.?????[!3]?[!1].*.sql # delete all files not in march and not day 1
  $ rm *.?????[!3][!0]?.*.sql # delete all files not in march and not day 11, 21, or 31

tree
  $ tree # draw tree structure of folders

find
  $ find . -name *.plugin
  $ find . -name *.plugin 2>/dev/null
  $ find /media/seagate/media/ -name Thumbs.db -exec rm {} \; # delete files across folders
  $ find . -name "*.js" -exec java -jar compiler.jar --js {} --js_output_file new{} \;
  $ find . -name "*.jpg" -exec convert {} -resize 1920x1080 ../assets_youtube/{} \; 

find unique list of file types
  $ find ../ -type f | awk -F. '!a[$NF]++{print $NF}'

find and execute command on files across files
  $ find /media/seagate/media/ -name Thumbs.db -exec rm {} \; # delete files across folders
  $ find ../ -type f \( -name "*.jpg" -o name "*.JPG" \) -exec rm {} \;
  $ find ../ -type f -name "*.JPG" -exec rename s/JPG/jpg/ {} \;

find a file anywhere on the disk and ignore the "Permission denied" messages
  $ find / -name Wire.h 2>&1 | grep -v "Permission denied"

grep
  $ grep -r "progressive" . 

rename 
  $ rename s/JPG/jpg/ *

copy files
  $ mv SRC DEST
  $ cp SRC DEST
  $ scp SRC DEST
  $ rsync SRC DEST

synchronize two external hard disks, dry run, real thing, ending slash required

  rsync --dry-run --itemize-changes -avh /media/john/My\ Passport/pub/ /media/john/Seagate\ Expansion\ Drive/pub/
  
  rsync -avh /media/john/My\ Passport/pub/ /media/john/Seagate\ Expansion\ Drive/pub/
  
  --dry-run
  --itemize-changes
  --delete, delete extraneous files from destination (dest will mirror src)
  -a --archive, equivalent to -rlptgoD
    -r --recursive
    -l --links, copy symlinks as symlinks
    -p --perms, preserve permissions
    -t --times, preserve modification times
    -g --group, preserve group
    -o --owner, preserve owner
    -D preserve device files, preserve special files
  -v --verbose
  -h --human-readable number formats

sync songs from hard disk to phone, skipping the cover art

  rsync --delete -avh -e "ssh -p 2222" --exclude '*.jpg' /media/passport/pub/songs/ '192.168.1.100:/storage/emulated/0/media/songs/'