Cat blocking when piping output from /usr/bin/gssproxy (`timeout -k 1 1 /usr/bin/gssproxy | cat` does not terminate) The 2019 Stack Overflow Developer Survey Results Are InPiping output from a segfaulting programssh “-f” don't give back hand in bash when listening to stdout/stderrTimeout doesn't occur when reading from fifo using `read`Formatting grep output with awk. Simple case and background caseWhen does cat finish reading from a pipe?Piping sed/grep output does not workWhy doesn't file redirection to and from a named pipe work, but piping to cat does?Opening named pipe blocks forever, if pipe is deleted without being connectedCapturing all output from piping input into a cli programSetting variable output from timeout

Spanish for "widget"

Why isn't airport relocation done gradually?

How long do I have to send payment?

Should I use my personal or workplace e-mail when registering to external websites for work purpose?

How come people say “Would of”?

How to create dashed lines/arrows in Illustrator

Why do UK politicians seemingly ignore opinion polls on Brexit?

Patience, young "Padovan"

Does a dangling wire really electrocute me if I'm standing in water?

How to manage monthly salary

Dual Citizen. Exited the US on Italian passport recently

Is domain driven design an anti-SQL pattern?

Inversion Puzzle

Pristine Bit Checking

"To split hairs" vs "To be pedantic"

A poker game description that does not feel gimmicky

Does it makes sense to buy a new cycle to learn riding?

"Riffle" two strings

Where to refill my bottle in India?

Monty Hall variation

"What time...?" or "At what time...?" - what is more grammatically correct?

Time travel alters history but people keep saying nothing's changed

What can other administrators access on my machine?

What tool would a Roman-age civilization have to grind silver and other metals into dust?

Cat blocking when piping output from /usr/bin/gssproxy (`timeout -k 1 1 /usr/bin/gssproxy | cat` does not terminate)

The 2019 Stack Overflow Developer Survey Results Are InPiping output from a segfaulting programssh “-f” don't give back hand in bash when listening to stdout/stderrTimeout doesn't occur when reading from fifo using `read`Formatting grep output with awk. Simple case and background caseWhen does cat finish reading from a pipe?Piping sed/grep output does not workWhy doesn't file redirection to and from a named pipe work, but piping to cat does?Opening named pipe blocks forever, if pipe is deleted without being connectedCapturing all output from piping input into a cli programSetting variable output from timeout

.everyoneloves__top-leaderboard:empty,.everyoneloves__mid-leaderboard:empty,.everyoneloves__bot-mid-leaderboard:empty margin-bottom:0;

I use gssproxy under Arch Linux, in particular

Name : gssproxy
Version : 0.8.0-1

I encountered the following behavior: When trying to pipe the output of
/usr/bin/gssproxy
like so

/usr/bin/gssproxy | cat

it blocks.
However, when I just run this command:
/usr/bin/gssproxy it does not block, but creates another process in the background

root 13720 0.0 0.0 59732 584 ? Ssl 11:44 0:00 /usr/bin/gssproxy

and exists.

I acknowledge that there is probably no point in piping the output of gssproxy, but nevertheless I am still wondering why this behavior occurs? In particular, what causes cat to block?

EDIT:

By blocking, I mean that the following command:

timeout -k 1 1 /usr/bin/gssproxy | cat,

does not terminate, while

timeout -k 1 1 /usr/bin/gssproxy

terminates immediately. Both command spawn gssproxy process in the background. I am wondering why the first command
does not terminate after 1 second as I would expect?

edited 2 days ago

asked Apr 6 at 11:49

MLStudent

112

New contributor

1

How do you see that it's blocked? gssproxy is a daemon program. I would not be surprised if it simple tests to see whether it's standard output is connected to a terminal or not, and if it's not it may simply decide to not output anything (because it thinks it's running as it should be running, in the background). If it's connected to a terminal, it obviously re-executes itself in the background.

– Kusalananda♦
Apr 6 at 12:33

It might be similar to this: setsid sleep 5 doesn't block (and forks sleep), setsid sleep 5 | cat blocks for the duration of sleep.

– A.B
Apr 6 at 16:49

I observed the following situation: [root@d48293f221d9]# timeout -k 1 1 /usr/bin/gssproxy | cat ^C [root@d48293f221d9]# ps aux | grep gssproxy root 24131 0.0 0.0 59732 588 ? Ssl 07:44 0:00 /usr/bin/gssproxy where timeout does not cause a termination after 1 second, as I would expect. Would you have any idea why?

– MLStudent
2 days ago

add a comment |

I use gssproxy under Arch Linux, in particular

Name : gssproxy
Version : 0.8.0-1

I encountered the following behavior: When trying to pipe the output of
/usr/bin/gssproxy
like so

/usr/bin/gssproxy | cat

it blocks.
However, when I just run this command:
/usr/bin/gssproxy it does not block, but creates another process in the background

root 13720 0.0 0.0 59732 584 ? Ssl 11:44 0:00 /usr/bin/gssproxy

and exists.

I acknowledge that there is probably no point in piping the output of gssproxy, but nevertheless I am still wondering why this behavior occurs? In particular, what causes cat to block?

EDIT:

By blocking, I mean that the following command:

timeout -k 1 1 /usr/bin/gssproxy | cat,

does not terminate, while

timeout -k 1 1 /usr/bin/gssproxy

terminates immediately. Both command spawn gssproxy process in the background. I am wondering why the first command
does not terminate after 1 second as I would expect?

edited 2 days ago

asked Apr 6 at 11:49

MLStudent

112

New contributor

1

How do you see that it's blocked? gssproxy is a daemon program. I would not be surprised if it simple tests to see whether it's standard output is connected to a terminal or not, and if it's not it may simply decide to not output anything (because it thinks it's running as it should be running, in the background). If it's connected to a terminal, it obviously re-executes itself in the background.

– Kusalananda♦
Apr 6 at 12:33

It might be similar to this: setsid sleep 5 doesn't block (and forks sleep), setsid sleep 5 | cat blocks for the duration of sleep.

– A.B
Apr 6 at 16:49

I observed the following situation: [root@d48293f221d9]# timeout -k 1 1 /usr/bin/gssproxy | cat ^C [root@d48293f221d9]# ps aux | grep gssproxy root 24131 0.0 0.0 59732 588 ? Ssl 07:44 0:00 /usr/bin/gssproxy where timeout does not cause a termination after 1 second, as I would expect. Would you have any idea why?

– MLStudent
2 days ago

add a comment |

I use gssproxy under Arch Linux, in particular

Name : gssproxy
Version : 0.8.0-1

I encountered the following behavior: When trying to pipe the output of
/usr/bin/gssproxy
like so

/usr/bin/gssproxy | cat

it blocks.
However, when I just run this command:
/usr/bin/gssproxy it does not block, but creates another process in the background

root 13720 0.0 0.0 59732 584 ? Ssl 11:44 0:00 /usr/bin/gssproxy

and exists.

I acknowledge that there is probably no point in piping the output of gssproxy, but nevertheless I am still wondering why this behavior occurs? In particular, what causes cat to block?

EDIT:

By blocking, I mean that the following command:

timeout -k 1 1 /usr/bin/gssproxy | cat,

does not terminate, while

timeout -k 1 1 /usr/bin/gssproxy

terminates immediately. Both command spawn gssproxy process in the background. I am wondering why the first command
does not terminate after 1 second as I would expect?

edited 2 days ago

asked Apr 6 at 11:49

MLStudent

112

New contributor

I use gssproxy under Arch Linux, in particular

Name : gssproxy
Version : 0.8.0-1

I encountered the following behavior: When trying to pipe the output of
/usr/bin/gssproxy
like so

/usr/bin/gssproxy | cat

it blocks.
However, when I just run this command:
/usr/bin/gssproxy it does not block, but creates another process in the background

root 13720 0.0 0.0 59732 584 ? Ssl 11:44 0:00 /usr/bin/gssproxy

and exists.

I acknowledge that there is probably no point in piping the output of gssproxy, but nevertheless I am still wondering why this behavior occurs? In particular, what causes cat to block?

EDIT:

By blocking, I mean that the following command:

timeout -k 1 1 /usr/bin/gssproxy | cat,

does not terminate, while

timeout -k 1 1 /usr/bin/gssproxy

terminates immediately. Both command spawn gssproxy process in the background. I am wondering why the first command
does not terminate after 1 second as I would expect?

pipe timeout

edited 2 days ago

asked Apr 6 at 11:49

MLStudent

112

New contributor

edited 2 days ago

asked Apr 6 at 11:49

MLStudent

112

New contributor

edited 2 days ago

asked Apr 6 at 11:49

MLStudent

112

New contributor

asked Apr 6 at 11:49

MLStudent

112

asked Apr 6 at 11:49

MLStudent

112

New contributor

MLStudent is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.

1

How do you see that it's blocked? gssproxy is a daemon program. I would not be surprised if it simple tests to see whether it's standard output is connected to a terminal or not, and if it's not it may simply decide to not output anything (because it thinks it's running as it should be running, in the background). If it's connected to a terminal, it obviously re-executes itself in the background.

– Kusalananda♦
Apr 6 at 12:33

It might be similar to this: setsid sleep 5 doesn't block (and forks sleep), setsid sleep 5 | cat blocks for the duration of sleep.

– A.B
Apr 6 at 16:49

I observed the following situation: [root@d48293f221d9]# timeout -k 1 1 /usr/bin/gssproxy | cat ^C [root@d48293f221d9]# ps aux | grep gssproxy root 24131 0.0 0.0 59732 588 ? Ssl 07:44 0:00 /usr/bin/gssproxy where timeout does not cause a termination after 1 second, as I would expect. Would you have any idea why?

– MLStudent
2 days ago

add a comment |

1

How do you see that it's blocked? gssproxy is a daemon program. I would not be surprised if it simple tests to see whether it's standard output is connected to a terminal or not, and if it's not it may simply decide to not output anything (because it thinks it's running as it should be running, in the background). If it's connected to a terminal, it obviously re-executes itself in the background.

– Kusalananda♦
Apr 6 at 12:33

It might be similar to this: setsid sleep 5 doesn't block (and forks sleep), setsid sleep 5 | cat blocks for the duration of sleep.

– A.B
Apr 6 at 16:49

I observed the following situation: [root@d48293f221d9]# timeout -k 1 1 /usr/bin/gssproxy | cat ^C [root@d48293f221d9]# ps aux | grep gssproxy root 24131 0.0 0.0 59732 588 ? Ssl 07:44 0:00 /usr/bin/gssproxy where timeout does not cause a termination after 1 second, as I would expect. Would you have any idea why?

– MLStudent
2 days ago

How do you see that it's blocked? gssproxy is a daemon program. I would not be surprised if it simple tests to see whether it's standard output is connected to a terminal or not, and if it's not it may simply decide to not output anything (because it thinks it's running as it should be running, in the background). If it's connected to a terminal, it obviously re-executes itself in the background.

– Kusalananda♦
Apr 6 at 12:33

It might be similar to this: setsid sleep 5 doesn't block (and forks sleep), setsid sleep 5 | cat blocks for the duration of sleep.

– A.B
Apr 6 at 16:49

I observed the following situation: [root@d48293f221d9]# timeout -k 1 1 /usr/bin/gssproxy | cat ^C [root@d48293f221d9]# ps aux | grep gssproxy root 24131 0.0 0.0 59732 588 ? Ssl 07:44 0:00 /usr/bin/gssproxy where timeout does not cause a termination after 1 second, as I would expect. Would you have any idea why?

– MLStudent
2 days ago

add a comment |

1 Answer
1

active

oldest

votes

As @Kusalananda, mentions gssproxy runs as a daemon, the parent process probably wait's untill it's child exits.

Here's a short shell script which emulates the same situation.

$ cat t1
#!/bin/bash
sleep 10 &

$ date; ./t1 | cat ; date
Sun Apr 7 10:59:02 BST 2019
Sun Apr 7 10:59:12 BST 2019

The date commands are there purely to show that after the subprocess exists (10 seconds) cat terminates

answered 2 days ago

X Tian

7,83512237

Thanks! But why is it that timeout -k 1 1 /usr/bin/gssproxy | cat does not cause the gssproxy process to exit?

– MLStudent
2 days ago

add a comment |

Your Answer

StackExchange.ready(function()
var channelOptions =
tags: "".split(" "),
id: "106"
;
initTagRenderer("".split(" "), "".split(" "), channelOptions);

StackExchange.using("externalEditor", function()
// Have to fire editor after snippets, if snippets enabled
if (StackExchange.settings.snippets.snippetsEnabled)
StackExchange.using("snippets", function()
createEditor();
);

else
createEditor();

);

function createEditor()
StackExchange.prepareEditor(
heartbeatType: 'answer',
autoActivateHeartbeat: false,
convertImagesToLinks: false,
noModals: true,
showLowRepImageUploadWarning: true,
reputationToPostImages: null,
bindNavPrevention: true,
postfix: "",
imageUploader:
brandingHtml: "Powered by u003ca class="icon-imgur-white" href="https://imgur.com/"u003eu003c/au003e",
contentPolicyHtml: "User contributions licensed under u003ca href="https://creativecommons.org/licenses/by-sa/3.0/"u003ecc by-sa 3.0 with attribution requiredu003c/au003e u003ca href="https://stackoverflow.com/legal/content-policy"u003e(content policy)u003c/au003e",
allowUrls: true
,
onDemand: true,
discardSelector: ".discard-answer"
,immediatelyShowMarkdownHelp:true
);

);

MLStudent is a new contributor. Be nice, and check out our Code of Conduct.

draft saved

draft discarded

StackExchange.ready(
function ()
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2funix.stackexchange.com%2fquestions%2f510894%2fcat-blocking-when-piping-output-from-usr-bin-gssproxy-timeout-k-1-1-usr-bin%23new-answer', 'question_page');

);

Post as a guest

Name

Required, but never shown

1 Answer
1

active

oldest

votes

1 Answer
1

active

oldest

votes

As @Kusalananda, mentions gssproxy runs as a daemon, the parent process probably wait's untill it's child exits.

Here's a short shell script which emulates the same situation.

$ cat t1
#!/bin/bash
sleep 10 &

$ date; ./t1 | cat ; date
Sun Apr 7 10:59:02 BST 2019
Sun Apr 7 10:59:12 BST 2019

The date commands are there purely to show that after the subprocess exists (10 seconds) cat terminates

answered 2 days ago

X Tian

7,83512237

Thanks! But why is it that timeout -k 1 1 /usr/bin/gssproxy | cat does not cause the gssproxy process to exit?

– MLStudent
2 days ago

add a comment |

As @Kusalananda, mentions gssproxy runs as a daemon, the parent process probably wait's untill it's child exits.

Here's a short shell script which emulates the same situation.

$ cat t1
#!/bin/bash
sleep 10 &

$ date; ./t1 | cat ; date
Sun Apr 7 10:59:02 BST 2019
Sun Apr 7 10:59:12 BST 2019

The date commands are there purely to show that after the subprocess exists (10 seconds) cat terminates

answered 2 days ago

X Tian

7,83512237

Thanks! But why is it that timeout -k 1 1 /usr/bin/gssproxy | cat does not cause the gssproxy process to exit?

– MLStudent
2 days ago

add a comment |

As @Kusalananda, mentions gssproxy runs as a daemon, the parent process probably wait's untill it's child exits.

Here's a short shell script which emulates the same situation.

$ cat t1
#!/bin/bash
sleep 10 &

$ date; ./t1 | cat ; date
Sun Apr 7 10:59:02 BST 2019
Sun Apr 7 10:59:12 BST 2019

The date commands are there purely to show that after the subprocess exists (10 seconds) cat terminates

answered 2 days ago

X Tian

7,83512237

As @Kusalananda, mentions gssproxy runs as a daemon, the parent process probably wait's untill it's child exits.

Here's a short shell script which emulates the same situation.

$ cat t1
#!/bin/bash
sleep 10 &

$ date; ./t1 | cat ; date
Sun Apr 7 10:59:02 BST 2019
Sun Apr 7 10:59:12 BST 2019

The date commands are there purely to show that after the subprocess exists (10 seconds) cat terminates

answered 2 days ago

X Tian

7,83512237

answered 2 days ago

X Tian

7,83512237

answered 2 days ago

X Tian

7,83512237

answered 2 days ago

X Tian

7,83512237

Thanks! But why is it that timeout -k 1 1 /usr/bin/gssproxy | cat does not cause the gssproxy process to exit?

– MLStudent
2 days ago

add a comment |

Thanks! But why is it that timeout -k 1 1 /usr/bin/gssproxy | cat does not cause the gssproxy process to exit?

– MLStudent
2 days ago

Thanks! But why is it that timeout -k 1 1 /usr/bin/gssproxy | cat does not cause the gssproxy process to exit?

– MLStudent
2 days ago

add a comment |

MLStudent is a new contributor. Be nice, and check out our Code of Conduct.

draft saved

draft discarded

MLStudent is a new contributor. Be nice, and check out our Code of Conduct.

Thanks for contributing an answer to Unix & Linux Stack Exchange!

Please be sure to answer the question. Provide details and share your research!

But avoid …

Asking for help, clarification, or responding to other answers.

Making statements based on opinion; back them up with references or personal experience.

To learn more, see our tips on writing great answers.

draft saved

draft discarded

Post as a guest

Name

Required, but never shown

Name

Required, but never shown

Name

Required, but never shown

This page is only for reference, If you need detailed information, please check here

搜尋此網誌

Ygtjki

1 Answer
1

Your Answer

Post as a guest

1 Answer
1

1 Answer
1

Post as a guest

Popular posts from this blog

1 Answer 1

Your Answer

Sign up or log in

Post as a guest

Post as a guest

1 Answer 1

1 Answer 1

Sign up or log in

Post as a guest

Post as a guest

Sign up or log in

Post as a guest

Sign up or log in

Post as a guest

Sign up or log in

Post as a guest

Popular posts from this blog

1 Answer
1

1 Answer
1

1 Answer
1