basic_system_file_3.sh

#!/bin/bash

. ./build_env_0.sh

ln -svf ../proc/mounts ${OS}/etc/mtab

echo "mtlab created"

cat > ${OS}/etc/passwd << "EOF"
root::0:0:root:/root:/bin/ash
EOF

echo "created passwd"

cat > ${OS}/etc/group << "EOF"
root:x:0:
bin:x:1:
sys:x:2:
kmem:x:3:
tty:x:4:
daemon:x:6:
disk:x:8:
dialout:x:10:
video:x:12:
utmp:x:13:
usb:x:14:
EOF

echo "created group"

cat > ${OS}/etc/fstab << "EOF"
# file system  mount-point  type   options          dump  fsck
#                                                         order

rootfs          /               auto    defaults        1      1
proc            /proc           proc    defaults        0      0
sysfs           /sys            sysfs   defaults        0      0
devpts          /dev/pts        devpts  gid=4,mode=620  0      0
tmpfs           /dev/shm        tmpfs   defaults        0      0
EOF

echo "created fstab"

cat > ${OS}/etc/profile << "EOF"
export PATH=/bin:/usr/bin

if [ `id -u` -eq 0 ] ; then
        PATH=/bin:/sbin:/usr/bin:/usr/sbin
        unset HISTFILE
fi

# Set up some environment variables.
export USER=`id -un`
export LOGNAME=$USER
export HOSTNAME=`/bin/hostname`
export HISTSIZE=1000
export HISTFILESIZE=1000
export PAGER='/bin/more '
export EDITOR='/bin/vi'
EOF

echo "created profile"

echo "linux" > ${OS}/etc/HOSTNAME

cat > ${OS}/etc/issue<< "EOF"
Linux base os 1.0
Kernel \r on an \m

EOF

echo "created issue"

cat > ${OS}/etc/inittab<< "EOF"
::sysinit:/etc/rc.d/startup

tty1::respawn:/sbin/getty 38400 tty1
tty2::respawn:/sbin/getty 38400 tty2
tty3::respawn:/sbin/getty 38400 tty3
tty4::respawn:/sbin/getty 38400 tty4
tty5::respawn:/sbin/getty 38400 tty5
tty6::respawn:/sbin/getty 38400 tty6

::shutdown:/etc/rc.d/shutdown
::ctrlaltdel:/sbin/reboot
EOF

echo "created inittab"

cat > ${OS}/etc/mdev.conf<< "EOF"
# Devices:
# Syntax: %s %d:%d %s
# devices user:group mode

# null does already exist; therefore ownership has to
# be changed with command
null    root:root 0666  @chmod 666 $MDEV
zero    root:root 0666
grsec   root:root 0660
full    root:root 0666

random  root:root 0666
urandom root:root 0444
hwrandom root:root 0660

# console does already exist; therefore ownership has to
# be changed with command
console root:tty 0600 @mkdir -pm 755 fd && cd fd && for x in 0 1 2 3 ; do ln -sf /proc/self/fd/$x $x; done

kmem    root:root 0640
mem     root:root 0640
port    root:root 0640
ptmx    root:tty 0666

# ram.*
ram([0-9]*)     root:disk 0660 >rd/%1
loop([0-9]+)    root:disk 0660 >loop/%1
sd[a-z].*       root:disk 0660 */lib/mdev/usbdisk_link
hd[a-z][0-9]*   root:disk 0660 */lib/mdev/ide_links

tty             root:tty 0666
tty[0-9]        root:root 0600
tty[0-9][0-9]   root:tty 0660
ttyO[0-9]*      root:tty 0660
pty.*           root:tty 0660
vcs[0-9]*       root:tty 0660
vcsa[0-9]*      root:tty 0660

ttyLTM[0-9]     root:dialout 0660 @ln -sf $MDEV modem
ttySHSF[0-9]    root:dialout 0660 @ln -sf $MDEV modem
slamr           root:dialout 0660 @ln -sf $MDEV slamr0
slusb           root:dialout 0660 @ln -sf $MDEV slusb0
fuse            root:root  0666

# misc stuff
agpgart         root:root 0660  >misc/
psaux           root:root 0660  >misc/
rtc             root:root 0664  >misc/

# input stuff
event[0-9]+     root:root 0640 =input/
ts[0-9]         root:root 0600 =input/

# v4l stuff
vbi[0-9]        root:video 0660 >v4l/
video[0-9]      root:video 0660 >v4l/

# load drivers for usb devices
usbdev[0-9].[0-9]       root:root 0660 */lib/mdev/usbdev
usbdev[0-9].[0-9]_.*    root:root 0660
EOF

echo "created mdev conf"

cat > ${OS}/boot/grub/grub.cfg<< "EOF"
set default=0
set timeout=5

set root=(hd0,1)

menuentry "Linux minimal" {
        linux   /boot/vmlinuz-4.16.3 root=/dev/sda1 ro quiet
}
EOF

echo "created grup.cfg"

touch ${OS}/var/run/utmp ${OS}/var/log/{btmp,lastlog,wtmp}

chmod -v 664 ${OS}/var/run/utmp ${OS}/var/log/lastlog

echo "basic file creation done"