7.3. Setting up the Environment

The standard I/O streams of the initial shell process is connected with /dev/console. However, the testsuite of some packages may expect the standard I/O streams to be connected with a “real” TTY device node. Spawn a new shell process on the TTY device with agetty:

agetty -n -l /bin/bash tty0

If you are working via a serial console, replace tty0 with the name of the serial console device node, for example ttyS0.

The command above spawns a new shell process on the TTY device specified in the command, and the initial shell process will run in background as aninit process with very limited functions. The new shell process will output:

bash: cannot set terminal process group (-1): Inappropriate ioctl for device
bash: no job control in this shell

This is normal because the shell is not assigned with a controlling terminal yet. Now set up controlling terminal and environment variables:

exec setsid -c /usr/bin/env -i  \
    HOME=/root                  \
    TERM="$TERM"                \
    PS1='(lfs) \u:\w\$ '        \
    PATH=/usr/bin:/usr/sbin     \
    /bin/bash --login +h

The command replace the current shell process with a new shell process, with controlling terminal set up.

The -i option given to the env command will clear all variables of the environment. After that, only the HOME, TERM, PS1, and PATH variables are set again. The TERM=$TERM construct will set the TERM variable to the default value specified by agetty. This variable is needed for programs like vim and less to operate properly. If other variables are desired, such as CFLAGS or CXXFLAGS, this is a good place to set them again.

Notice that /tools/bin is not in the PATH. This means that the cross toolchain will no longer be used in the building environment. This occurs when the shell does not “remember” the locations of executed binaries—for this reason, hashing is switched off by passing the +h option to bash.

Note that the bash prompt will say I have no name! This is normal because the /etc/passwd file has not been created yet.