[Touch-packages] [Bug 1394136] Re: if statement with pipe to grep randomly fails if pipefail is set
This is not a bug, although some might disagree with the current behavior of bash. With a command like 'yes | grep -q .', because the grep terminates early and the yes is writing past the end of the pipe buffer, the yes process is _always_ terminated with a SIGPIPE signal (which translates to a return value of 141). Combined with the pipefail option, the whole command is considered to have failed. pipefail should be used scarcely, that's why it is not enabled by default. -- You received this bug notification because you are a member of Ubuntu Touch seeded packages, which is subscribed to bash in Ubuntu. https://bugs.launchpad.net/bugs/1394136 Title: if statement with pipe to grep randomly fails if pipefail is set Status in bash package in Ubuntu: Confirmed Bug description: The following bash script will fail randomly on trusty but when tested on saucy it worked all the time. On the system we test we have kvm installed and the if statement should evaluate to false and we should see ten PASS lines and no Error. And this should happen all the time. == #!/bin/bash set -eu set -o pipefail if ! lsmod | grep -q -e ^kvm_intel -e ^kvm_amd ; then echo 'Error: check that virtualisation is enabled in your BIOS' else echo "PASS" fi === As can be seen if I run it 10 times I get 2 PASS and 8 failures === kerrin@kerrin-HP-Z620-Workstation:~/ce_build$ for i in $(seq 0 9) ; do bash test-simple.bash ; done PASS PASS Error: check that virtualisation is enabled in your BIOS Error: check that virtualisation is enabled in your BIOS Error: check that virtualisation is enabled in your BIOS Error: check that virtualisation is enabled in your BIOS Error: check that virtualisation is enabled in your BIOS Error: check that virtualisation is enabled in your BIOS Error: check that virtualisation is enabled in your BIOS Error: check that virtualisation is enabled in your BIOS === Now if I turn off the pipefail then the script passes all the time and just prints out 10 PASS lines. The script uses bash, grep and lsmod and I have the following versions on trusty of them kerrin@kerrin-HP-Z620-Workstation:~/ce_build$ dpkg -l | grep bash ii bash 4.3-7ubuntu1.5 amd64GNU Bourne Again SHell ii bash-completion 1:2.1-4 all programmable completion for the bash shell ii command-not-found 0.3ubuntu12 all Suggest installation of packages in interactive bash sessions kerrin@kerrin-HP-Z620-Workstation:~/ce_build$ dpkg -l | grep grep ii grep 2.16-1 amd64GNU grep, egrep and fgrep kerrin@kerrin-HP-Z620-Workstation:~/ce_build$ dpkg -l | grep kmod ii kmod 15-0ubuntu6 amd64tools for managing Linux kernel modules ii libkmod2:amd6415-0ubuntu6 amd64libkmod shared library ii module-init-tools 15-0ubuntu6 all transitional dummy package (module-init-tools to kmod) To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/bash/+bug/1394136/+subscriptions -- Mailing list: https://launchpad.net/~touch-packages Post to : touch-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~touch-packages More help : https://help.launchpad.net/ListHelp
[Touch-packages] [Bug 1394136] Re: if statement with pipe to grep randomly fails if pipefail is set
We can also see the following result: errin@kerrin-HP-Z620-Workstation:~/ce_build$ lsmod | grep -q -e ^kvm_amd -e ^kvm_intel; echo $? 141 kerrin@kerrin-HP-Z620-Workstation:~/ce_build$ lsmod | grep -q -e ^kvm_amd -e ^kvm_intel; echo $? 141 kerrin@kerrin-HP-Z620-Workstation:~/ce_build$ lsmod | grep -q -e ^kvm_amd -e ^kvm_intel; echo $? 141 kerrin@kerrin-HP-Z620-Workstation:~/ce_build$ lsmod | grep -q -e ^kvm_amd -e ^kvm_intel; echo $? 0 kerrin@kerrin-HP-Z620-Workstation:~/ce_build$ lsmod | grep -q -e ^kvm_amd -e ^kvm_intel; echo $? 141 kerrin@kerrin-HP-Z620-Workstation:~/ce_build$ lsmod | grep -q -e ^kvm_amd -e ^kvm_intel; echo $? 141 One out of a lot passed. -- You received this bug notification because you are a member of Ubuntu Touch seeded packages, which is subscribed to bash in Ubuntu. https://bugs.launchpad.net/bugs/1394136 Title: if statement with pipe to grep randomly fails if pipefail is set Status in “bash” package in Ubuntu: Confirmed Bug description: The following bash script will fail randomly on trusty but when tested on saucy it worked all the time. On the system we test we have kvm installed and the if statement should evaluate to false and we should see ten PASS lines and no Error. And this should happen all the time. == #!/bin/bash set -eu set -o pipefail if ! lsmod | grep -q -e ^kvm_intel -e ^kvm_amd ; then echo 'Error: check that virtualisation is enabled in your BIOS' else echo PASS fi === As can be seen if I run it 10 times I get 2 PASS and 8 failures === kerrin@kerrin-HP-Z620-Workstation:~/ce_build$ for i in $(seq 0 9) ; do bash test-simple.bash ; done PASS PASS Error: check that virtualisation is enabled in your BIOS Error: check that virtualisation is enabled in your BIOS Error: check that virtualisation is enabled in your BIOS Error: check that virtualisation is enabled in your BIOS Error: check that virtualisation is enabled in your BIOS Error: check that virtualisation is enabled in your BIOS Error: check that virtualisation is enabled in your BIOS Error: check that virtualisation is enabled in your BIOS === Now if I turn off the pipefail then the script passes all the time and just prints out 10 PASS lines. The script uses bash, grep and lsmod and I have the following versions on trusty of them kerrin@kerrin-HP-Z620-Workstation:~/ce_build$ dpkg -l | grep bash ii bash 4.3-7ubuntu1.5 amd64GNU Bourne Again SHell ii bash-completion 1:2.1-4 all programmable completion for the bash shell ii command-not-found 0.3ubuntu12 all Suggest installation of packages in interactive bash sessions kerrin@kerrin-HP-Z620-Workstation:~/ce_build$ dpkg -l | grep grep ii grep 2.16-1 amd64GNU grep, egrep and fgrep kerrin@kerrin-HP-Z620-Workstation:~/ce_build$ dpkg -l | grep kmod ii kmod 15-0ubuntu6 amd64tools for managing Linux kernel modules ii libkmod2:amd6415-0ubuntu6 amd64libkmod shared library ii module-init-tools 15-0ubuntu6 all transitional dummy package (module-init-tools to kmod) To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/bash/+bug/1394136/+subscriptions -- Mailing list: https://launchpad.net/~touch-packages Post to : touch-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~touch-packages More help : https://help.launchpad.net/ListHelp
[Touch-packages] [Bug 1394136] Re: if statement with pipe to grep randomly fails if pipefail is set
But this seems to work kerrin@kerrin-HP-Z620-Workstation:~/ce_build$ echo kvm_intel xxx | grep -q -e ^kvm_amd -e ^kvm_intel; echo $? 0 -- You received this bug notification because you are a member of Ubuntu Touch seeded packages, which is subscribed to bash in Ubuntu. https://bugs.launchpad.net/bugs/1394136 Title: if statement with pipe to grep randomly fails if pipefail is set Status in “bash” package in Ubuntu: Confirmed Bug description: The following bash script will fail randomly on trusty but when tested on saucy it worked all the time. On the system we test we have kvm installed and the if statement should evaluate to false and we should see ten PASS lines and no Error. And this should happen all the time. == #!/bin/bash set -eu set -o pipefail if ! lsmod | grep -q -e ^kvm_intel -e ^kvm_amd ; then echo 'Error: check that virtualisation is enabled in your BIOS' else echo PASS fi === As can be seen if I run it 10 times I get 2 PASS and 8 failures === kerrin@kerrin-HP-Z620-Workstation:~/ce_build$ for i in $(seq 0 9) ; do bash test-simple.bash ; done PASS PASS Error: check that virtualisation is enabled in your BIOS Error: check that virtualisation is enabled in your BIOS Error: check that virtualisation is enabled in your BIOS Error: check that virtualisation is enabled in your BIOS Error: check that virtualisation is enabled in your BIOS Error: check that virtualisation is enabled in your BIOS Error: check that virtualisation is enabled in your BIOS Error: check that virtualisation is enabled in your BIOS === Now if I turn off the pipefail then the script passes all the time and just prints out 10 PASS lines. The script uses bash, grep and lsmod and I have the following versions on trusty of them kerrin@kerrin-HP-Z620-Workstation:~/ce_build$ dpkg -l | grep bash ii bash 4.3-7ubuntu1.5 amd64GNU Bourne Again SHell ii bash-completion 1:2.1-4 all programmable completion for the bash shell ii command-not-found 0.3ubuntu12 all Suggest installation of packages in interactive bash sessions kerrin@kerrin-HP-Z620-Workstation:~/ce_build$ dpkg -l | grep grep ii grep 2.16-1 amd64GNU grep, egrep and fgrep kerrin@kerrin-HP-Z620-Workstation:~/ce_build$ dpkg -l | grep kmod ii kmod 15-0ubuntu6 amd64tools for managing Linux kernel modules ii libkmod2:amd6415-0ubuntu6 amd64libkmod shared library ii module-init-tools 15-0ubuntu6 all transitional dummy package (module-init-tools to kmod) To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/bash/+bug/1394136/+subscriptions -- Mailing list: https://launchpad.net/~touch-packages Post to : touch-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~touch-packages More help : https://help.launchpad.net/ListHelp
[Touch-packages] [Bug 1394136] Re: if statement with pipe to grep randomly fails if pipefail is set
** Changed in: bash (Ubuntu) Status: New = Confirmed -- You received this bug notification because you are a member of Ubuntu Touch seeded packages, which is subscribed to bash in Ubuntu. https://bugs.launchpad.net/bugs/1394136 Title: if statement with pipe to grep randomly fails if pipefail is set Status in “bash” package in Ubuntu: Confirmed Bug description: The following bash script will fail randomly on trusty but when tested on saucy it worked all the time. On the system we test we have kvm installed and the if statement should evaluate to false and we should see ten PASS lines and no Error. And this should happen all the time. == #!/bin/bash set -eu set -o pipefail if ! lsmod | grep -q -e ^kvm_intel -e ^kvm_amd ; then echo 'Error: check that virtualisation is enabled in your BIOS' else echo PASS fi === As can be seen if I run it 10 times I get 2 PASS and 8 failures === kerrin@kerrin-HP-Z620-Workstation:~/ce_build$ for i in $(seq 0 9) ; do bash test-simple.bash ; done PASS PASS Error: check that virtualisation is enabled in your BIOS Error: check that virtualisation is enabled in your BIOS Error: check that virtualisation is enabled in your BIOS Error: check that virtualisation is enabled in your BIOS Error: check that virtualisation is enabled in your BIOS Error: check that virtualisation is enabled in your BIOS Error: check that virtualisation is enabled in your BIOS Error: check that virtualisation is enabled in your BIOS === Now if I turn off the pipefail then the script passes all the time and just prints out 10 PASS lines. The script uses bash, grep and lsmod and I have the following versions on trusty of them kerrin@kerrin-HP-Z620-Workstation:~/ce_build$ dpkg -l | grep bash ii bash 4.3-7ubuntu1.5 amd64GNU Bourne Again SHell ii bash-completion 1:2.1-4 all programmable completion for the bash shell ii command-not-found 0.3ubuntu12 all Suggest installation of packages in interactive bash sessions kerrin@kerrin-HP-Z620-Workstation:~/ce_build$ dpkg -l | grep grep ii grep 2.16-1 amd64GNU grep, egrep and fgrep kerrin@kerrin-HP-Z620-Workstation:~/ce_build$ dpkg -l | grep kmod ii kmod 15-0ubuntu6 amd64tools for managing Linux kernel modules ii libkmod2:amd6415-0ubuntu6 amd64libkmod shared library ii module-init-tools 15-0ubuntu6 all transitional dummy package (module-init-tools to kmod) To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/bash/+bug/1394136/+subscriptions -- Mailing list: https://launchpad.net/~touch-packages Post to : touch-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~touch-packages More help : https://help.launchpad.net/ListHelp
