Difference between revisions of "Quick Reference"
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This page is a quick reference guide or a "cheatsheet" to assist with the initial learning curve. Once full familiarity with the development environment is established, this quick reference will likely no longer be needed. | This page is a quick reference guide or a "cheatsheet" to assist with the initial learning curve. Once full familiarity with the development environment is established, this quick reference will likely no longer be needed. | ||
Revision as of 12:17, 27 November 2013
This page is a quick reference guide or a "cheatsheet" to assist with the initial learning curve. Once full familiarity with the development environment is established, this quick reference will likely no longer be needed.
Contents
Working With the Terminal
Use minicom to bring up a serial terminal. To configure the serial console, run sudo minicom -s. The settings needed for configuring minicom can be found on this page. Select, Save as dfl, to save the settings you have configured to be the default settings whenever you run minicom. Use minicom -o to start minicom more quickly; the -o option tells minicom to start without sending AT commands to initialize a modem.
Editing a File
EMAC OE provides simple text editing capabilities for making changes to configuration files and scripts. Major editing tasks should be performed on a desktop system first, copying the desired files back to the target board. There are two text editors available on standard EMAC OE builds: vi and nano. vi is a very common text editor available on almost every Unix-like OS. nano is a more conventional text editor that can be easier to use for those not familiar with vi.
To edit a file with vi, run the command:
root@emac-oe:~# vi <filename>
To edit a file with nano, run the command:
root@emac-oe:~# nano <filename>
For a more detailed overview, see this page
Making Changes To The Target Machine's Fileystem
By default, the flash filesystem on most EMAC devices is mounted read-only. To make changes to the filesystem, it will have to be remounted as read-write. This can be done with the following command:
root@emac-oe:~# mount -o remount,rw /
To mount the filesystem as read-only again (without rebooting), type:
root@emac-oe:~# mount -o remount,ro /
Mounting a Flash Filesystem
There are four steps to mounting a flash filesystem on our EMAC OE machine:
-
Determine which device node is assigned to the flash device.
root@emac-oe:~# dmesg | tail -n 15
-
Determine which partition to mount.
-
Determine where to mount the device.
root@emac-oe:~# mkdir /mnt/myflash -
Mount the device.
root@emac-oe:~# mount /dev/sda1 /mnt/myflash
 | NOTE: You must have root permissions to perform some of the following steps. Make sure you are logged in as the root user prior to performing the following steps. The su command can be useful for this. The filesystem will also need to be mounted read/write in order to create the directory mentioned below. See the section regarding remounting the root filesystem as read/write (above) to see how to do this. |
For detailed instructions, please see the Mounting a Flash Filesystem page.
Network Interfaces
The ifup and ifdown commands may be used to enable (or, respectively, disable) network interfaces based on interface definitions in the file /etc/network/interfaces.
An example of using the ifup command:
root@emac-oe:~# ifup eth0
An example of using the ifdown command:
root@emac-oe:~# ifdown eth0
To temporarily configure the eth0 interface to have a static IP address, 192.168.1.125, to use a DNS server at 192.168.1.25, and to use a gateway at 192.168.1.1:
root@emac-oe:~# ifconfig eth0 up 192.168.1.125 netmask 255.255.255.0
root@emac-oe:~# route add default gw 192.168.1.1
root@emac-oe:~# echo "nameserver 192.168.1.25" > /etc/resolv.conf
Remote Access
To access an EMAC product remotely, it is easiest to use ssh and scp for remote command execution and remote file transfer respectively.
To log into a system with the IP address 10.0.2.41, enter the following command:
developer@ldc:~# ssh root@10.0.2.41
To execute a command on a remote system without opening a shell on the remote system (in this example, ls -la):
developer@ldc:~# ssh root@10.0.2.41 'ls -la'
To send the file example.text to the /home directory of a system with the IP address 10.0.2.41, enter the following command:
developer@ldc:~# scp example.text root@10.0.2.41:/home
Running a User Program
When a user program is uploaded, sometimes it does not have execute permissions. Use the following steps to ensure that your program functions properly.
-
Navigate to the directory that the application was uploaded to (e.g. /tmp):
root@emac-oe~:$ cd /tmp
-
Make the application file executable:
root@emac-oe~:$ chmod u+x <filename> -
Run the application:
root@emac-oe~:$ ./<filename>
