Get latest output of a running command

up vote
2
down vote

favorite

I have a command running for a long time (which I dont want to disturb). However I would like to keep check on the process (most of the time remotely). I am constantly monitoring the process via commands like top, iotop, stat etc. the process is a terminal based process which wasnt started via screen or tmux or similar. So the only way to check the output is using a physical access.

I know that /proc contains lot of info about the process. So I was wondering if it also can display the output (or even just the last batch of output -- char/word/line). I searched in /proc/<pid>/fd, but coundnt find anything useful.

Below is the output of ls -l /proc/26745/fd/*

lrwx------ 1 user user 64 Oct 28 13:19 /proc/26745/fd/0 -> /dev/pts/17
lrwx------ 1 user user 64 Oct 28 13:19 /proc/26745/fd/1 -> /dev/pts/17
lrwx------ 1 user user 64 Sep 27 22:27 /proc/26745/fd/2 -> /dev/pts/17

Any pointers?

asked 3 hours ago

Mike V.D.C.

1263

add a commentÂ |Â

up vote
2
down vote

favorite

Below is the output of ls -l /proc/26745/fd/*

lrwx------ 1 user user 64 Oct 28 13:19 /proc/26745/fd/0 -> /dev/pts/17
lrwx------ 1 user user 64 Oct 28 13:19 /proc/26745/fd/1 -> /dev/pts/17
lrwx------ 1 user user 64 Sep 27 22:27 /proc/26745/fd/2 -> /dev/pts/17

Any pointers?

asked 3 hours ago

Mike V.D.C.

1263

add a commentÂ |Â

up vote
2
down vote

favorite

Below is the output of ls -l /proc/26745/fd/*

lrwx------ 1 user user 64 Oct 28 13:19 /proc/26745/fd/0 -> /dev/pts/17
lrwx------ 1 user user 64 Oct 28 13:19 /proc/26745/fd/1 -> /dev/pts/17
lrwx------ 1 user user 64 Sep 27 22:27 /proc/26745/fd/2 -> /dev/pts/17

Any pointers?

asked 3 hours ago

Mike V.D.C.

1263

Below is the output of ls -l /proc/26745/fd/*

lrwx------ 1 user user 64 Oct 28 13:19 /proc/26745/fd/0 -> /dev/pts/17
lrwx------ 1 user user 64 Oct 28 13:19 /proc/26745/fd/1 -> /dev/pts/17
lrwx------ 1 user user 64 Sep 27 22:27 /proc/26745/fd/2 -> /dev/pts/17

Any pointers?

monitoring proc output

asked 3 hours ago

Mike V.D.C.

1263

asked 3 hours ago

Mike V.D.C.

1263

asked 3 hours ago

Mike V.D.C.

1263

asked 3 hours ago

Mike V.D.C.

1263

asked 3 hours ago

Mike V.D.C.

1263

add a commentÂ |Â

1 Answer
1

active

oldest

votes

up vote
2
down vote

I would use strace for that:

strace -qfp PID -e trace=write -e write=1,2

That will trace all write(2) system calls of PID and its child processes, and hexdump the data written to file descriptors 1 and 2.

Of course, that won't let you see what the process has already written to the tty, but will start monitoring all writes from a point on.

Also, strace is not amenable to change its output format -- you should explore using gdb(1) or write a small program using ptrace(2) if you need more flexibility.

edited 1 hour ago

answered 2 hours ago

mosvy

3,190119

add a commentÂ |Â

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',
convertImagesToLinks: false,
noModals: false,
showLowRepImageUploadWarning: true,
reputationToPostImages: null,
bindNavPrevention: true,
postfix: "",
onDemand: true,
discardSelector: ".discard-answer"
,immediatelyShowMarkdownHelp:true
);

);

draft saved

draft discarded

StackExchange.ready(
function ()
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2funix.stackexchange.com%2fquestions%2f478214%2fget-latest-output-of-a-running-command%23new-answer', 'question_page');

);

Post as a guest

Name

1 Answer
1

active

oldest

votes

1 Answer
1

active

oldest

votes

up vote
2
down vote

I would use strace for that:

strace -qfp PID -e trace=write -e write=1,2

That will trace all write(2) system calls of PID and its child processes, and hexdump the data written to file descriptors 1 and 2.

Of course, that won't let you see what the process has already written to the tty, but will start monitoring all writes from a point on.

Also, strace is not amenable to change its output format -- you should explore using gdb(1) or write a small program using ptrace(2) if you need more flexibility.

edited 1 hour ago

answered 2 hours ago

mosvy

3,190119

add a commentÂ |Â

up vote
2
down vote

I would use strace for that:

strace -qfp PID -e trace=write -e write=1,2

That will trace all write(2) system calls of PID and its child processes, and hexdump the data written to file descriptors 1 and 2.

Of course, that won't let you see what the process has already written to the tty, but will start monitoring all writes from a point on.

Also, strace is not amenable to change its output format -- you should explore using gdb(1) or write a small program using ptrace(2) if you need more flexibility.

edited 1 hour ago

answered 2 hours ago

mosvy

3,190119

add a commentÂ |Â

up vote
2
down vote

I would use strace for that:

strace -qfp PID -e trace=write -e write=1,2

That will trace all write(2) system calls of PID and its child processes, and hexdump the data written to file descriptors 1 and 2.

Of course, that won't let you see what the process has already written to the tty, but will start monitoring all writes from a point on.

Also, strace is not amenable to change its output format -- you should explore using gdb(1) or write a small program using ptrace(2) if you need more flexibility.

edited 1 hour ago

answered 2 hours ago

mosvy

3,190119

I would use strace for that:

strace -qfp PID -e trace=write -e write=1,2

That will trace all write(2) system calls of PID and its child processes, and hexdump the data written to file descriptors 1 and 2.

Of course, that won't let you see what the process has already written to the tty, but will start monitoring all writes from a point on.

Also, strace is not amenable to change its output format -- you should explore using gdb(1) or write a small program using ptrace(2) if you need more flexibility.

edited 1 hour ago

answered 2 hours ago

mosvy

3,190119

edited 1 hour ago

answered 2 hours ago

mosvy

3,190119

answered 2 hours ago

mosvy

3,190119

answered 2 hours ago

mosvy

3,190119

add a commentÂ |Â

draft saved

draft discarded

draft saved

draft discarded

Post as a guest

Name

Search This Blog

Iyfjky