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Message #131578
[Bug 1483440] Re: odd behavior with /proc/net/route reading via sh 'read'
Patch accepted upstream and queued for stable.
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https://bugs.launchpad.net/bugs/1483440
Title:
odd behavior with /proc/net/route reading via sh 'read'
Status in linux package in Ubuntu:
In Progress
Bug description:
I saw some strange behavior when one of my scripts started failing to
get the data it was looking for out of /proc/net/route
$ uname -r
$ dpkg -S /boot/vmlinux-$(uname -r)
linux-image-4.1.0-3-generic: /boot/vmlinuz-4.1.0-3-generic
$ id -u
1000
$ cp /proc/net/route /tmp/route
$ diff /proc/net/route /tmp/route
$ md5sum /proc/net/route /tmp/route
4b3663ec7554cf91764106ea9dcc2ada /proc/net/route
4b3663ec7554cf91764106ea9dcc2ada /tmp/route
## just cat the file
$ cat /proc/net/route
Iface Destination Gateway Flags RefCnt Use Metric Mask MTU Window IRTT
eth0 00000000 01A8F50A 0003 0 0 0 00000000 00 0
eth0 00A8F50A 00000000 0001 0 0 0 00F8FFFF 00 0
virbr0 007AA8C0 00000000 0001 0 0 0 00FFFFFF 00 0
## try to read it with sh while loop
$ sh -c 'while read line; do echo line: $line; done' < /proc/net/route
line: Iface Destination Gateway Flags RefCnt Use Metric Mask MTU Window IRTT
line: eth0 00A8F50A 00000000 0001 0 0 0 00F8FFFF 0 0 0
line: virbr0 007AA8C0 00000000 0001 0 0 0 00FFFFFF 0 0 0
## odd, where did the first line go?
##
## maybe its still there if we cat
$ cat /proc/net/route | sh -c 'while read line; do echo line: $line; done'
line: Iface Destination Gateway Flags RefCnt Use Metric Mask MTU Window IRTT
line: eth0 00000000 01A8F50A 0003 0 0 0 00000000 0 0 0
line: eth0 00A8F50A 00000000 0001 0 0 0 00F8FFFF 0 0 0
line: virbr0 007AA8C0 00000000 0001 0 0 0 00FFFFFF 0 0 0
## Yep, still there.
## as expected, the copied file shows sane behavior
$ sh -c 'while read line; do echo line: $line; done' < /tmp/route
line: Iface Destination Gateway Flags RefCnt Use Metric Mask MTU Window IRTT
line: eth0 00000000 01A8F50A 0003 0 0 0 00000000 0 0 0
line: eth0 00A8F50A 00000000 0001 0 0 0 00F8FFFF 0 0 0
line: virbr0 007AA8C0 00000000 0001 0 0 0 00FFFFFF 0 0 0
ProblemType: Bug
DistroRelease: Ubuntu 15.10
Package: linux-image-4.1.0-3-generic 4.1.0-3.3
ProcVersionSignature: User Name 4.1.0-3.3-generic 4.1.3
Uname: Linux 4.1.0-3-generic x86_64
AlsaDevices:
total 0
crw-rw---- 1 root audio 116, 1 Aug 10 23:52 seq
crw-rw---- 1 root audio 116, 33 Aug 10 23:52 timer
AplayDevices: Error: [Errno 2] No such file or directory: 'aplay'
ApportVersion: 2.18-0ubuntu6
Architecture: amd64
ArecordDevices: Error: [Errno 2] No such file or directory: 'arecord'
AudioDevicesInUse: Error: command ['fuser', '-v', '/dev/snd/seq', '/dev/snd/timer'] failed with exit code 1:
Date: Mon Aug 10 23:55:09 2015
IwConfig: Error: [Errno 2] No such file or directory: 'iwconfig'
MachineType: HP ProLiant DL360 Gen9
PciMultimedia:
ProcEnviron:
TERM=xterm-256color
PATH=(custom, no user)
XDG_RUNTIME_DIR=<set>
LANG=en_US.UTF-8
SHELL=/bin/bash
ProcFB: 0 EFI VGA
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-4.1.0-3-generic root=UUID=ebea97f1-7014-4fac-bc87-c8ff465c566f ro --- console=ttyS1,115200
RelatedPackageVersions:
linux-restricted-modules-4.1.0-3-generic N/A
linux-backports-modules-4.1.0-3-generic N/A
linux-firmware 1.146
RfKill: Error: [Errno 2] No such file or directory: 'rfkill'
SourcePackage: linux
UdevLog: Error: [Errno 2] No such file or directory: '/var/log/udev'
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 03/05/2015
dmi.bios.vendor: HP
dmi.bios.version: P89
dmi.chassis.type: 23
dmi.chassis.vendor: HP
dmi.modalias: dmi:bvnHP:bvrP89:bd03/05/2015:svnHP:pnProLiantDL360Gen9:pvr:cvnHP:ct23:cvr:
dmi.product.name: ProLiant DL360 Gen9
dmi.sys.vendor: HP
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