your huwawei modem is giving error: > > Cannot open /dev/ttyUSB0: Device or resource busy

If your huwawei modem is giving u the error :

> > Cannot open /dev/ttyUSB0: Device or resource busy

 if you do this command: 

 lsusb

 Bus 002 Device 019: ID 12d1:1003 Huawei Technologies Co., Ltd. E220 HSDPA Modem / E230/E270 HSDPA/HSUPA Mode

 and you do this command

ls -ll /dev

crw-rw----  1 root uucp      188,   0 Jun 27 14:18 ttyUSB0
crw-rw----  1 root uucp      188,   1 Jun 27 14:18 ttyUSB1
 and you have those ttyUSB 

and dmesg gives you this outpu

dmesg

[20567.359261] option 2-1:1.0: GSM modem (1-port) converter detected
[20567.359379] usb 2-1: GSM modem (1-port) converter now attached to ttyUSB0
[20567.362205] option 2-1:1.1: GSM modem (1-port) converter detected
[20567.362296] usb 2-1: GSM modem (1-port) converter now attached to ttyUSB1
[20567.363034] scsi47 : usb-storage 2-1:1.2
[20567.364026] scsi48 : usb-storage 2-1:1.3
[20568.368922] scsi 47:0:0:0: CD-ROM            HUAWEI   Mass Storage     2.31 PQ: 0 ANSI: 2
[20568.371161] scsi 48:0:0:0: Direct-Access     HUAWEI   MMC Storage      2.31 PQ: 0 ANSI: 2
[20568.371366] sd 48:0:0:0: Attached scsi generic sg2 type 0
[20568.380524] sr1: scsi-1 drive
[20568.380662] sr 47:0:0:0: Attached scsi CD-ROM sr1
[20568.380742] sr 47:0:0:0: Attached scsi generic sg3 type 5
[20568.383510] sd 48:0:0:0: [sdb] Attached SCSI removable disk

and comgt is giving u the similar

comgt -x -d /dev/ttyUSB0
High speed overide (115200 is now 57600).
SIM ready
Waiting for Registration..(120 sec max)
Registered on Home network: "xxxxx",2
Signal Quality: 26,99

check if the directory lock is in /var  and create one

mkdir /var/lock

ls -ll /var/lock
total 4
-rw-r--r-- 1 root root 11 Jun 27 13:11 LCK..ttyUSB0

Good luck and enjoy the surfing, do not forget to like my coments if ithas helped you