Commands tagged qr (5)

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Find default gateway

Connect to google talk through ssh by setting your IM client to use the localhost 5432 port
If your firewall or proxy at your location prevents connection to a particular host or port, you can use ssh to tunnel to your home server and do it there instead.

Calculate files' size

Create a mirror of a local folder, on a remote server
Create a exact mirror of the local folder "/root/files", on remote server 'remote_server' using SSH command (listening on port 22) (all files & folders on destination server/folder will be deleted)

Get your external IP address if your machine has a DNS entry
Using DynDNS or a similar service not only allows access to your home machine from outside without needing to know what IP the ISP has assigned to it but it also comes in handy if you want to know your external IP address. The only purpose of the sed command is to remove the leading "host.na.me has address " part from the output. If you don't need to discard it you can simply use $ host $HOSTNAME

Find directories under home directory with 777 permissions, change to 755, and list them on console

Virtualbox rsync copy (without defining any virtualbox configuration)
That is, after running `vagrant ssh-config` to determine ports and ip's: $ vagrant ssh-config Host default HostName 127.0.0.1 User vagrant Port 2200 UserKnownHostsFile /dev/null StrictHostKeyChecking no PasswordAuthentication no IdentityFile /Users/romanvg/tmp/.vagrant/machines/default/virtualbox/private_key IdentitiesOnly yes LogLevel FATAL

Quick screenshot
Requires ImageMagick. Takes a screenshot 5 seconds after it's run and saves it as desktop_screenshot.jpg Particularly handy when made into a menu option or button.

Multi line grep using sed and specifying open/close tags
Working with log files that contains variable length messages wrapped between open and close tags it may be useful to filter the messages upon a keyword. This works fine with GNU sed version 4.2 or higher, so pay attention to some unix distros (solaris, hp-ux, etc.). Linux should be ok.

recursively change file name from uppercase to lowercase (or viceversa)
or, to process a single directory: $ for f in *; do mv $f `echo $f |tr '[:upper:]' '[:lower:]'`; done


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