Tag: shell

Backing up and verifying files in Mac OS

There are some interesting backup tools for system backups (Time Machine) but I want to just be able to copy and verify a directory (and its children).  I’ve heard that the commercial product Retrospect provides copy and verify functionality, but I’m cheap.

This is the method that I used.  I’d be interested on hearing feedback about it:

# Copy the files using ditto 
$ ditto /Volumes/Backup/columbus_da/ /Volumes/ghingexternal/columbus_da

# Get md5s for the original and copied files
$ find /Volumes/ghingexternal/columbus_day/ -exec md5 '{}' \; > md5s-new.txt
$ find /Volumes/Backup/columbus_day/ -exec md5 '{}' \; > md5s-old.txt

# Strip out the directory prefix from the md5 files
$ mv md5s-old.txt md5s-old.txt.bak
$ mv md5s-new.txt md5s-new.txt.bak
$ sed 's/\/Volumes\/ghingexternal\///' md5s-new.txt.bak > md5s-new.txt
$ sed 's/\/Volumes\/Backup\///' md5s-old.txt.bak > md5s-old.txt

# Compare the md5s of the copied files
$ diff md5s-old.txt md5s-new.txt

passing grep results to other unix commands

This is old news to a lot of folks, but new and powerful to me.

Search for text in files and move matching files

$ grep --files-with-matches --null foo * | xargs --null -I xxx mv xxx dir_for_foos/

The above command searches for the string foo in all files in the current subdirectory.  It then moves each file to a specified directory.

Read a list of files from a text file and move those files somewhere

$ xargs -a ok.txt  -I xxx mv xxx /var/lib/accounting/joblogs/parsed

screen cheatsheet

I’ve been using the unix screen command a lot lately, and enough to want to learn more.

I used to just scroll through windows with CTRL-a n and CTRL-a p, but now I have a ton of windows in my screen session, so I want to be able to navigate easier.

According to the manpage, you can automatically set the title of a window, but I think it’s nice to do it interactively because the general task that will identify the window’s functionality might not easily be reflected in a path or command.

You can also use screen to copy/paste text between windows:

  • Enter copy mode: CTRL-a [
  • Start/End selecting text to copy: SPACE
  • Paste text CTRL-a ]