Tag Archives: command line

Killing “find” Errors

I’ve used the unix filesystem search utility find for many years. Though, like most things, until forced to learn its deeper secrets, I generally get by with only the most basic knowledge.

One of the cool things about find is that you can specify a search and then execute an action on the results, all in one command.

This example is probably my most common use of find:

find . -type d -name .svn -exec rm -fr {} \;

This means: find, in the current directory (.), a directory (-type d), named .svn (-name .svn), and for every result (-exec) remove that directory (rm -fr {}) .  The “{}” represents the matched path string, and the “\;” is required to end the “-exec” command.

Here’s a sample of what this looks like, including output:

$ find . -type d -name .svn -exec rm -fr {} \;
find: ./.svn: No such file or directory
find: ./getid3-2.0.0b4/.svn: No such file or directory
find: ./getid3-2.0.0b4/extras/.svn: No such file or directory
find: ./getid3-2.0.0b4/getid3/.svn: No such file or directory

This is great, and I’ve used this exact syntax for years. But today I ran into a problem. I wanted to run this exact command as part of a custom build script in Xcode. When this command ran I had 81 errors popup in my build results! What happened is that all thos “No such file or directory” messages are actually errors, and Xcode reported them as such.

The solution is to add one extra argument: -depth . This causes find to do a depth-first traversal of the sub-directories being searched. That is, find will check the contents of directories before acting (eg, running an -exec command) on the directory in question. The default is to act on the directory (in our case, removing it) before attempting to visit it’s contents. So after we removed the directory, find was still trying to look at it; -depth fixes that.

So, the final answer is, I now use:

find . -type d -name .svn -depth -exec rm -fr {} \;

Yes, this is a slightly verbose explanation for something so simple, but maybe it will help someone else.

Use vi key bindings in bash

A long time ago I used ksh with vi key bindings, and life was good.

Then I moved on to bash, but for some reason, I never investigated using vi key bindings. I simply lived with the defaults (which, for the record, are emacs-like key bindings).

So, just the other day I said to myself, “Self, I want to use vi key bindings in bash. I want to again experience the joy of traversing and editing my command line in COMMAND MODE. I want the speed and the power of my precious vi (well, I use vim) at my finger tips. And I NO LONGER want to waste time holding arrow keys or to think about using emacs-like commands.”

So, I fired up google.com; low and behold I stumbled onto this little post about using vi key bindings in bash and zsh. So sweet!

In a nutshell, the bash command to enable vi mode is:

set -o vi

This can be set in your .bashrc file, and if it doesn’t pickup when you start a new terminal session, add something like this to your .profile or .bash_profile:

if [ -f ~/.bashrc ]; then
. ~/.bashrc

With vi mode enabled, you’ll start your bash session in insert mode, so things should behave as normal. But, to turn on the power, just hit the ESC key to enter COMMAND MODE. 🙂 Now all your vi commands are availble. Move to end of line with “$”, beginning of line with “^”, delete a word with “dw”, etc.


Fight Back! (When VPN Clients Mis-Behave)

I have to use VPNs at work. Specifically, to access my production webservers (etc), I have to use a Cisco VPN client. Sadly, the VPN concentrator overrides my choice of allowing local LAN access. So, when I am on the VPN, I have my DNS options changed so I can’t use any local servers. This is a serious, serious pain. So painful in fact, that many times instead of fight with it, I simply would run a Windows session in VMware (on my Mac) and connect the VPN there. This has drawbacks too, but it’s better than not having local network access.

So I set out to find a solution and I found a post by loudhush which described using the scutil to modify DNS network settings after connecting to a Cisco VPN. This was great, but I needed something a bit handier.

So, I cranked out the following which goes in my /Users/username/.profile:

# .profile or .bash_profile
function myvpn {
function myworkdns {
printf "get State:/Network/Service/com.cisco.VPN/DNS\nd.add ServerAddresses *,\nd.add SearchDomains * example.com, other.example.com\nset State:/Network/Service/com.cisco.VPN/DNS" | sudo scutil

These are bash functions which i run from the command line. (I also find the Client GUI Cisco to be a pain, and prefer command line)

So, obviously, you’ll need to substitute in your Cisco VPN profile name ( found in /etc/opt/cisco-vpnclient/Profiles), your VPN username, your DNS server IP addresses, and your DNS search domains to your legitimate values.

To use, run Terminal, then type myvpn. The VPN client will prompt you for your username and password. You’ll then have to hit CTRL+Z to suspend the VPN client so the script can run the DNS updates; this part uses sudo to run the command as root, so you will probably need to type your Mac password immediately after hitting CTRL+Z. If you didn’t want to bother with the command line VPN client, you could just use your GUI Cisco VPN client, then run myworkdns from Terminal, which will still probably prompt you for your Mac password.

Hope others find this useful. If I find a cleaner way, I’ll post that too.