/dev/null read only, part 2

/dev/null read only, part 2

,

Pada post sebelumnya, /dev/null jadi read only untuk user non-root, Finally solved!

Terakhir boot openSUSE sebelum ke Tanjung kemarin, /dev/null read_only terjadi lagi. Jadi aku putuskan ini jadi PR buat di Tanjung. Tapi udah di Tanjung, boot ke GUI semua berjalan normal. Itu sebabnya aku post comment ini.

Balik ke Mangkajang, /dev/null read_only terjadi lagi. Arghhh…. What is missing? Why? How can?

Error yg muncul ketika gagal ke GNOME ada pada file “~/.xsession-errors“. Jadi login ke session failsafe, aku buka file itu. Intinya, gagal karena user ku nggak bisa akses /dev/null.

/etc/X11/xdm/Xsession: line 24: /dev/null: Permission denied
/etc/X11/xdm/Xsession: line 25: /dev/null: Permission denied
/etc/X11/xdm/Xsession: line 26: /dev/null: Permission denied
/etc/X11/xdm/Xsession: line 27: /dev/null: Permission denied
/etc/X11/xdm/Xsession: line 53: /dev/null: Permission denied
/etc/X11/xinit/xinitrc.common: line 40: /dev/null: Permission denied
/etc/X11/xim: Checking whether an input method should be started.
/etc/profile: line 40: /dev/null: Permission denied
/etc/profile: line 92: /dev/null: Permission denied
/etc/profile: line 93: /dev/null: Permission denied
/etc/profile.d/profile.sh: line 118: /dev/null: Permission denied
/etc/X11/xim: user environment variable LANG=en_US.UTF-8
sourcing /etc/sysconfig/language to get the value of INPUT_METHOD
INPUT_METHOD is not set or empty (no user selected input method).
Trying to start a default input method for the locale en_US.UTF-8 ...
There is no default input method for the current locale.
/etc/profile: line 40: /dev/null: Permission denied
/etc/profile: line 92: /dev/null: Permission denied
/etc/profile: line 93: /dev/null: Permission denied
/etc/profile.d/profile.sh: line 118: /dev/null: Permission denied
/etc/X11/xdm/sys.xsession: line 28: /dev/null: Permission denied
/etc/X11/xdm/sys.xsession: line 29: /dev/null: Permission denied
/etc/X11/xdm/sys.xsession: line 30: /dev/null: Permission denied
/etc/X11/xdm/sys.xsession: line 31: /dev/null: Permission denied
Couldn't open /dev/null: Permission denied

Ketika error /dev/null read_only terjadi, ada 3 null pada direktori /dev.

laptop:/root # ls -l /dev | grep null
-rw-r--r--  1 root root             0 2008-01-10 20:09 null
-rw-r--r--  1 root root          1340 2008-01-10 20:07 null.2008-01-10.0
lrwxrwxrwx  1 root root            17 2008-01-10 20:07 null.current -> null.2008-01-10.0

Ada yg ganjil dari 3 file itu. Tipe file /dev/null yg nggak berbeda :

laptop:/root # file /dev/null
/dev/null: empty

Sedangkan jika normal, seharusnya :

laptop:/root # ls -l /dev/null
crw-rw-rw- 1 root root 1, 3 2007-09-22 03:12 /dev/null
laptop:/root # file /dev/null
/dev/null: character special (1/3)

Kemudian, ukuran file /dev/null.2008-01-10.0 yg besar. Berbekal iseng, aku buat :

laptop:/root # cat /dev/null.2008-01-10.0
Jan 10 20:07:24 MYT: WvDial< *1>: WvDial: Internet dialer version 1.56 (abuild@kalman)
Jan 10 20:07:24 MYT: WvDial< *1>: Initializing modem.
Jan 10 20:07:24 MYT: WvDial< *1>: Sending: ATZ
Jan 10 20:07:24 MYT: WvDial Modem< *1>: ATZ
Jan 10 20:07:24 MYT: WvDial Modem< *1>: OK
Jan 10 20:07:24 MYT: WvDial< *1>: Sending: ATQ0 V1 E1 S0=0 &C1 &D2 +FCLASS=0
Jan 10 20:07:25 MYT: WvDial Modem< *1>: ATQ0 V1 E1 S0=0 &C1 &D2 +FCLASS=0
Jan 10 20:07:25 MYT: WvDial Modem< *1>: OK
Jan 10 20:07:25 MYT: WvDial< *1>: Sending: AT+CGDCONT=1,"IP","quasar.net.id"
Jan 10 20:07:25 MYT: WvDial Modem< *1>: AT+CGDCONT=1,"IP","quasar.net.id"
Jan 10 20:07:25 MYT: WvDial Modem< *1>: OK
Jan 10 20:07:25 MYT: WvDial< *1>: Sending: ATM1
Jan 10 20:07:25 MYT: WvDial Modem< *1>: ATM1
Jan 10 20:07:25 MYT: WvDial Modem< *1>: OK
Jan 10 20:07:25 MYT: WvDial< *1>: Modem initialized.
Jan 10 20:07:25 MYT: WvDial< *1>: Sending: ATDT*99#
Jan 10 20:07:25 MYT: WvDial< *1>: Waiting for carrier.
Jan 10 20:07:25 MYT: WvDial Modem< *1>: ATDT*99#
Jan 10 20:07:25 MYT: WvDial Modem< *1>: CONNECT
Jan 10 20:07:25 MYT: WvDial Modem< *1>: ~[7f]}#@!}!} } }2}#}$@#}!}$}%\}"}&} }*} } g}%~
Jan 10 20:07:25 MYT: WvDial< *1>: Carrier detected.  Waiting for prompt.
Jan 10 20:07:28 MYT: WvDial Modem< *1>: ~[7f]}#@!}!} } }2}#}$@#}!}$}%\}"}&} }*} } g}%~
Jan 10 20:07:28 MYT: WvDial< *1>: PPP negotiation detected.

Ternyata ada yg coba connect ke internet! Dan kalo lihat di /var/log/message, ternyata ntpdate mencoba untuk menghubungi id.pool.ntp.org

Iya sih, aku emang set NTP daemon untuk otomatis connect ke server id.pool.ntpd.org saat booting. wvdial sukses, ntpdate bisa connect ke id.pool.ntp.org dan jam sistem di-update.

Ok, sementara ini kesimpulannya /dev/null jadi read only jika:

  1. Saat booting, phone modem udah terhubung ke laptop.
  2. ntpdate mencoba connect ke internet dan berhubung modemnya terpasang, wvdial melakukan tugasnya.
  3. Entah mengapa, ouput wvdial saat membuat koneksi ditulis ke /dev/null.
  4. Meskipun akhirnya wvdial berhasil membuat koneksi dan ntpdate sukses update jam sistem, tapi /dev/null udah nggak asli (bingung cari kata yg tepat), jadi dibuatlah file /dev/null baru yg read only untuk user non-root :frown:

So, biar /dev/null nggak read only, saat booting jangan hubungkan modem ke laptop!!!

Hihihi… Lebih canggih ketimbang “chmod go+w /dev/nullp:

/dev/null read only, part 2

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