Using “tail” to follow a file without displaying the most recent linesHow can I do the equivalent of tail -f with ls?Observe multiple log files in one outputMaking less's follow option show line movementtail -f but suck in content of the file first (aka `cat -f`)Using tail to follow daily log file in BashTail -f the most recent log fileOnly output most recent 10 (or n) lines of a lengthy command outputtail display whole file and then only changesFor a given directory, how do I concatenate the tail end of recently modified files to a new file?Using head and tail to grab different sets of lines and saving into same file
What's the meaning of "Sollensaussagen"?
Can I hook these wires up to find the connection to a dead outlet?
Car headlights in a world without electricity
How to Prove P(a) → ∀x(P(x) ∨ ¬(x = a)) using Natural Deduction
Is it possible to map the firing of neurons in the human brain so as to stimulate artificial memories in someone else?
One verb to replace 'be a member of' a club
Forgetting the musical notes while performing in concert
What historical events would have to change in order to make 19th century "steampunk" technology possible?
How to compactly explain secondary and tertiary characters without resorting to stereotypes?
How do conventional missiles fly?
How can I deal with my CEO asking me to hire someone with a higher salary than me, a co-founder?
What is the most common color to indicate the input-field is disabled?
Is this draw by repetition?
Does int main() need a declaration on C++?
Machine learning testing data
How exploitable/balanced is this homebrew spell: Spell Permanency?
How to stretch the corners of this image so that it looks like a perfect rectangle?
Does the Idaho Potato Commission associate potato skins with healthy eating?
Sums of two squares in arithmetic progressions
How to remove border from elements in the last row?
Is it possible to create a QR code using text?
How do I exit BASH while loop using modulus operator?
If a warlock makes a Dancing Sword their pact weapon, is there a way to prevent it from disappearing if it's farther away for more than a minute?
Was the old ablative pronoun "med" or "mēd"?
Using “tail” to follow a file without displaying the most recent lines
How can I do the equivalent of tail -f with ls?Observe multiple log files in one outputMaking less's follow option show line movementtail -f but suck in content of the file first (aka `cat -f`)Using tail to follow daily log file in BashTail -f the most recent log fileOnly output most recent 10 (or n) lines of a lengthy command outputtail display whole file and then only changesFor a given directory, how do I concatenate the tail end of recently modified files to a new file?Using head and tail to grab different sets of lines and saving into same file
I would like use a program like tail to follow a file as it's being written to, but not display the most recent lines.
For instance, when following a new file, no text will be displayed while the file is less than 30 lines. After more than 30 lines are written to the file, lines will be written to the screen starting at line 1.
So as lines 31-40 are written to the file, lines 1-10 will be written to the screen.
If there is no easy way to do this with tail, maybe a there's a way to write to a new file a prior line from the first file each time the first file is extended by a line, and the tail that new file...
linux command-line tail
asked 2 hours ago
ridthyselfridthyself
111
New contributor
ridthyself is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
add a comment |
I would like use a program like tail to follow a file as it's being written to, but not display the most recent lines.
For instance, when following a new file, no text will be displayed while the file is less than 30 lines. After more than 30 lines are written to the file, lines will be written to the screen starting at line 1.
So as lines 31-40 are written to the file, lines 1-10 will be written to the screen.
If there is no easy way to do this with tail, maybe a there's a way to write to a new file a prior line from the first file each time the first file is extended by a line, and the tail that new file...
linux command-line tail
asked 2 hours ago
ridthyselfridthyself
111
New contributor
ridthyself is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
add a comment |
I would like use a program like tail to follow a file as it's being written to, but not display the most recent lines.
For instance, when following a new file, no text will be displayed while the file is less than 30 lines. After more than 30 lines are written to the file, lines will be written to the screen starting at line 1.
So as lines 31-40 are written to the file, lines 1-10 will be written to the screen.
If there is no easy way to do this with tail, maybe a there's a way to write to a new file a prior line from the first file each time the first file is extended by a line, and the tail that new file...
linux command-line tail
asked 2 hours ago
ridthyselfridthyself
111
New contributor
ridthyself is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
I would like use a program like tail to follow a file as it's being written to, but not display the most recent lines.
For instance, when following a new file, no text will be displayed while the file is less than 30 lines. After more than 30 lines are written to the file, lines will be written to the screen starting at line 1.
So as lines 31-40 are written to the file, lines 1-10 will be written to the screen.
If there is no easy way to do this with tail, maybe a there's a way to write to a new file a prior line from the first file each time the first file is extended by a line, and the tail that new file...
linux command-line tail
linux command-line tail
asked 2 hours ago
ridthyselfridthyself
111
New contributor
ridthyself is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
asked 2 hours ago
ridthyselfridthyself
111
New contributor
ridthyself is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
asked 2 hours ago
ridthyselfridthyself
111
New contributor
ridthyself is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
asked 2 hours ago
ridthyselfridthyself
111
asked 2 hours ago
ridthyselfridthyself
111
111
New contributor
ridthyself is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
New contributor
ridthyself is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
ridthyself is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
add a comment |
add a comment |
2 Answers
2
active
oldest
votes
Maybe buffer with awk:
tail -n +0 -f some/file | awk 'b[NR] = $0 NR > 30 print b[NR-30]; delete b[NR-30] END for (i = NR - 29; i <= NR; i++) print b[i]'
The awk code, expanded:
b[NR] = $0 # save the current line in a buffer array
NR > 30 # once we have more than 30 lines
print b[NR-30]; # print the line from 30 lines ago
delete b[NR-30]; # and delete it
END # once the pipe closes, print the rest
for (i = NR - 29; i <= NR; i++)
print b[i]
answered 1 hour ago
murumuru
36.8k589163
This works, but form the script I would expect it to work like tail, printing out a previous line as each new line is added to the file. Instead it prints out in spurts of ~70 lines after ~100 lines are added to the file. It does not print the most recent 30 lines, so it's pretty close...
– ridthyself
1 hour ago
@ridthyself if you have GNU awk, try adding afflush();after theprint b[NR-30];. Maybe the output is being buffered.
– muru
52 mins ago
add a comment |
This isn't very efficient, because it will re-read the file every two seconds, but will do the job:
watch 'tail -n40 /path/to/file | head -n10'
answered 2 hours ago
l0b0l0b0
28.7k19121249
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
);
);
ridthyself is a new contributor. Be nice, and check out our Code of Conduct.
Sign up or log in
StackExchange.ready(function ()
StackExchange.helpers.onClickDraftSave('#login-link');
var $window = $(window),
onScroll = function(e)
var $elem = $('.new-login-left'),
docViewTop = $window.scrollTop(),
docViewBottom = docViewTop + $window.height(),
elemTop = $elem.offset().top,
elemBottom = elemTop + $elem.height();
if ((docViewTop elemBottom))
StackExchange.using('gps', function() StackExchange.gps.track('embedded_signup_form.view', location: 'question_page' ); );
$window.unbind('scroll', onScroll);
;
$window.on('scroll', onScroll);
);
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
StackExchange.ready(
function ()
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2funix.stackexchange.com%2fquestions%2f510178%2fusing-tail-to-follow-a-file-without-displaying-the-most-recent-lines%23new-answer', 'question_page');
);
Post as a guest
Required, but never shown
2 Answers
2
active
oldest
votes
2 Answers
2
active
oldest
votes
active
oldest
votes
active
oldest
votes
Maybe buffer with awk:
tail -n +0 -f some/file | awk 'b[NR] = $0 NR > 30 print b[NR-30]; delete b[NR-30] END for (i = NR - 29; i <= NR; i++) print b[i]'
The awk code, expanded:
b[NR] = $0 # save the current line in a buffer array
NR > 30 # once we have more than 30 lines
print b[NR-30]; # print the line from 30 lines ago
delete b[NR-30]; # and delete it
END # once the pipe closes, print the rest
for (i = NR - 29; i <= NR; i++)
print b[i]
answered 1 hour ago
murumuru
36.8k589163
This works, but form the script I would expect it to work like tail, printing out a previous line as each new line is added to the file. Instead it prints out in spurts of ~70 lines after ~100 lines are added to the file. It does not print the most recent 30 lines, so it's pretty close...
– ridthyself
1 hour ago
@ridthyself if you have GNU awk, try adding afflush();after theprint b[NR-30];. Maybe the output is being buffered.
– muru
52 mins ago
add a comment |
Maybe buffer with awk:
tail -n +0 -f some/file | awk 'b[NR] = $0 NR > 30 print b[NR-30]; delete b[NR-30] END for (i = NR - 29; i <= NR; i++) print b[i]'
The awk code, expanded:
b[NR] = $0 # save the current line in a buffer array
NR > 30 # once we have more than 30 lines
print b[NR-30]; # print the line from 30 lines ago
delete b[NR-30]; # and delete it
END # once the pipe closes, print the rest
for (i = NR - 29; i <= NR; i++)
print b[i]
answered 1 hour ago
murumuru
36.8k589163
This works, but form the script I would expect it to work like tail, printing out a previous line as each new line is added to the file. Instead it prints out in spurts of ~70 lines after ~100 lines are added to the file. It does not print the most recent 30 lines, so it's pretty close...
– ridthyself
1 hour ago
@ridthyself if you have GNU awk, try adding afflush();after theprint b[NR-30];. Maybe the output is being buffered.
– muru
52 mins ago
add a comment |
Maybe buffer with awk:
tail -n +0 -f some/file | awk 'b[NR] = $0 NR > 30 print b[NR-30]; delete b[NR-30] END for (i = NR - 29; i <= NR; i++) print b[i]'
The awk code, expanded:
b[NR] = $0 # save the current line in a buffer array
NR > 30 # once we have more than 30 lines
print b[NR-30]; # print the line from 30 lines ago
delete b[NR-30]; # and delete it
END # once the pipe closes, print the rest
for (i = NR - 29; i <= NR; i++)
print b[i]
answered 1 hour ago
murumuru
36.8k589163
Maybe buffer with awk:
tail -n +0 -f some/file | awk 'b[NR] = $0 NR > 30 print b[NR-30]; delete b[NR-30] END for (i = NR - 29; i <= NR; i++) print b[i]'
The awk code, expanded:
b[NR] = $0 # save the current line in a buffer array
NR > 30 # once we have more than 30 lines
print b[NR-30]; # print the line from 30 lines ago
delete b[NR-30]; # and delete it
END # once the pipe closes, print the rest
for (i = NR - 29; i <= NR; i++)
print b[i]
answered 1 hour ago
murumuru
36.8k589163
edited 52 mins ago
answered 1 hour ago
murumuru
36.8k589163
answered 1 hour ago
murumuru
36.8k589163
answered 1 hour ago
murumuru
36.8k589163
36.8k589163
This works, but form the script I would expect it to work like tail, printing out a previous line as each new line is added to the file. Instead it prints out in spurts of ~70 lines after ~100 lines are added to the file. It does not print the most recent 30 lines, so it's pretty close...
– ridthyself
1 hour ago
@ridthyself if you have GNU awk, try adding afflush();after theprint b[NR-30];. Maybe the output is being buffered.
– muru
52 mins ago
add a comment |
This works, but form the script I would expect it to work like tail, printing out a previous line as each new line is added to the file. Instead it prints out in spurts of ~70 lines after ~100 lines are added to the file. It does not print the most recent 30 lines, so it's pretty close...
– ridthyself
1 hour ago
@ridthyself if you have GNU awk, try adding afflush();after theprint b[NR-30];. Maybe the output is being buffered.
– muru
52 mins ago
This works, but form the script I would expect it to work like tail, printing out a previous line as each new line is added to the file. Instead it prints out in spurts of ~70 lines after ~100 lines are added to the file. It does not print the most recent 30 lines, so it's pretty close...
– ridthyself
1 hour ago
This works, but form the script I would expect it to work like tail, printing out a previous line as each new line is added to the file. Instead it prints out in spurts of ~70 lines after ~100 lines are added to the file. It does not print the most recent 30 lines, so it's pretty close...
– ridthyself
1 hour ago
@ridthyself if you have GNU awk, try adding a
fflush(); after the print b[NR-30];. Maybe the output is being buffered.– muru
52 mins ago
@ridthyself if you have GNU awk, try adding a
fflush(); after the print b[NR-30];. Maybe the output is being buffered.– muru
52 mins ago
add a comment |
This isn't very efficient, because it will re-read the file every two seconds, but will do the job:
watch 'tail -n40 /path/to/file | head -n10'
answered 2 hours ago
l0b0l0b0
28.7k19121249
add a comment |
This isn't very efficient, because it will re-read the file every two seconds, but will do the job:
watch 'tail -n40 /path/to/file | head -n10'
answered 2 hours ago
l0b0l0b0
28.7k19121249
add a comment |
This isn't very efficient, because it will re-read the file every two seconds, but will do the job:
watch 'tail -n40 /path/to/file | head -n10'
answered 2 hours ago
l0b0l0b0
28.7k19121249
This isn't very efficient, because it will re-read the file every two seconds, but will do the job:
watch 'tail -n40 /path/to/file | head -n10'
answered 2 hours ago
l0b0l0b0
28.7k19121249
answered 2 hours ago
l0b0l0b0
28.7k19121249
answered 2 hours ago
l0b0l0b0
28.7k19121249
answered 2 hours ago
l0b0l0b0
28.7k19121249
28.7k19121249
add a comment |
add a comment |
ridthyself is a new contributor. Be nice, and check out our Code of Conduct.
ridthyself is a new contributor. Be nice, and check out our Code of Conduct.
ridthyself is a new contributor. Be nice, and check out our Code of Conduct.
ridthyself 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.
Sign up or log in
StackExchange.ready(function ()
StackExchange.helpers.onClickDraftSave('#login-link');
var $window = $(window),
onScroll = function(e)
var $elem = $('.new-login-left'),
docViewTop = $window.scrollTop(),
docViewBottom = docViewTop + $window.height(),
elemTop = $elem.offset().top,
elemBottom = elemTop + $elem.height();
if ((docViewTop elemBottom))
StackExchange.using('gps', function() StackExchange.gps.track('embedded_signup_form.view', location: 'question_page' ); );
$window.unbind('scroll', onScroll);
;
$window.on('scroll', onScroll);
);
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
StackExchange.ready(
function ()
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2funix.stackexchange.com%2fquestions%2f510178%2fusing-tail-to-follow-a-file-without-displaying-the-most-recent-lines%23new-answer', 'question_page');
);
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function ()
StackExchange.helpers.onClickDraftSave('#login-link');
var $window = $(window),
onScroll = function(e)
var $elem = $('.new-login-left'),
docViewTop = $window.scrollTop(),
docViewBottom = docViewTop + $window.height(),
elemTop = $elem.offset().top,
elemBottom = elemTop + $elem.height();
if ((docViewTop elemBottom))
StackExchange.using('gps', function() StackExchange.gps.track('embedded_signup_form.view', location: 'question_page' ); );
$window.unbind('scroll', onScroll);
;
$window.on('scroll', onScroll);
);
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function ()
StackExchange.helpers.onClickDraftSave('#login-link');
var $window = $(window),
onScroll = function(e)
var $elem = $('.new-login-left'),
docViewTop = $window.scrollTop(),
docViewBottom = docViewTop + $window.height(),
elemTop = $elem.offset().top,
elemBottom = elemTop + $elem.height();
if ((docViewTop elemBottom))
StackExchange.using('gps', function() StackExchange.gps.track('embedded_signup_form.view', location: 'question_page' ); );
$window.unbind('scroll', onScroll);
;
$window.on('scroll', onScroll);
);
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function ()
StackExchange.helpers.onClickDraftSave('#login-link');
var $window = $(window),
onScroll = function(e)
var $elem = $('.new-login-left'),
docViewTop = $window.scrollTop(),
docViewBottom = docViewTop + $window.height(),
elemTop = $elem.offset().top,
elemBottom = elemTop + $elem.height();
if ((docViewTop elemBottom))
StackExchange.using('gps', function() StackExchange.gps.track('embedded_signup_form.view', location: 'question_page' ); );
$window.unbind('scroll', onScroll);
;
$window.on('scroll', onScroll);
);
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
