Mrthdrb

What is the command to reset a PC without deleting any files

I probably found a bug with the sudo apt install function

Patience, young "Padovan"

Why don't electron-positron collisions release infinite energy?

Is Social Media Science Fiction?

What would happen to a modern skyscraper if it rains micro blackholes?

Is there a familial term for apples and pears?

Do airline pilots ever risk not hearing communication directed to them specifically, from traffic controllers?

I’m planning on buying a laser printer but concerned about the life cycle of toner in the machine

What is the offset in a seaplane's hull?

What do you call something that goes against the spirit of the law, but is legal when interpreting the law to the letter?

What do you call a Matrix-like slowdown and camera movement effect?

N.B. ligature in Latex

How do you conduct xenoanthropology after first contact?

Can you lasso down a wizard who is using the Levitate spell?

What is the white spray-pattern residue inside these Falcon Heavy nozzles?

declaring a variable twice in IIFE

How did the USSR manage to innovate in an environment characterized by government censorship and high bureaucracy?

How to make payment on the internet without leaving a money trail?

least quadratic residue under GRH: an EXPLICIT bound

What is the meaning of "of trouble" in the following sentence?

When blogging recipes, how can I support both readers who want the narrative/journey and ones who want the printer-friendly recipe?

Can a German sentence have two subjects?

How to report a triplet of septets in NMR tabulation?

Find the age of the oldest file in one line or return zero

Determining number of files in a directory without counting themCheck for subdirectoryAdd mtime to grep -c output and sort the output by mtimehow to find files of current date in remote server and copy those file to local server using rcp using shell scripting (ksh)?Search for files that contain a string and list their names sorted by the modified daterecursive search and print most recent tar.gz file in each dirFind and rm command deleted the files inside the directory and the directory itselfHow do I change the sorting method of files used by asterisk (*) in bash?Find files, print creation date and file namescp <source>:<filepath> <dest> works from command line, but cp: cannot stat error from script. Why?

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

4

1

I want to find the age of the oldest file in a certain directory or return 0 if there aren't any files in this directory. I also need a one-line command doing it. So far this is my command for finding the age in seconds of the oldest file in the directory:

expr $(($(date +%s) - $(stat -c %Y $(ls -lt /path/to/dir/ | tail -1 | awk 'print $NF'))))

The problem is that if there are no files it is returning the following error:

$ expr $(($(date +%s) - $(stat -c %Y $(ls -lt /path/to/dir/ | tail -1 | awk 'print $NF'))))
stat: cannot stat ‘0’: No such file or directory
-bash: 1554373460 - : syntax error: operand expected (error token is "- ")

So in this case I want the command to return just 0 and to suppress the error printout.

shell-script files directory

share|improve this question

asked Apr 4 at 10:26

Georgе StoyanovGeorgе Stoyanov

164421

• 
  
  
  

  
  2
  

  
  
  
  
  
  

  
  
  Out of curiosity, why does it have to be in one line? It's much less readable & maintainable that way.
  
  – Jeff Schaller♦
  Apr 4 at 10:30
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  I am passing this line to specialized software. Then according to the output of the command, I can trigger an alarm and if I make it on more than a single line, I need to write more complex logic. The idea is to check a specific directory where there should not be any files for more than 20 seconds, I want to trigger an alarm if the age of the oldest file is more than 30 seconds.
  
  – Georgе Stoyanov
  Apr 4 at 10:39
  
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  also I would be very happy if you have any ideas, how I can simplify my command for finding the age of the oldest file
  
  – Georgе Stoyanov
  Apr 4 at 10:41
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  ls -lt | tail -1 will give you the oldest file; you can parse out the date or go through the stat stuff without having to do a single line shell loop
  
  – mpez0
  Apr 4 at 20:06
  
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  @mpez0 this is exactly what I am doing, check my original post.
  
  – Georgе Stoyanov
  2 days ago
  

  
  
  
  

add a comment | 

4

1

I want to find the age of the oldest file in a certain directory or return 0 if there aren't any files in this directory. I also need a one-line command doing it. So far this is my command for finding the age in seconds of the oldest file in the directory:

expr $(($(date +%s) - $(stat -c %Y $(ls -lt /path/to/dir/ | tail -1 | awk 'print $NF'))))

The problem is that if there are no files it is returning the following error:

$ expr $(($(date +%s) - $(stat -c %Y $(ls -lt /path/to/dir/ | tail -1 | awk 'print $NF'))))
stat: cannot stat ‘0’: No such file or directory
-bash: 1554373460 - : syntax error: operand expected (error token is "- ")

So in this case I want the command to return just 0 and to suppress the error printout.

shell-script files directory

share|improve this question

asked Apr 4 at 10:26

Georgе StoyanovGeorgе Stoyanov

164421

• 
  
  
  

  
  2
  

  
  
  
  
  
  

  
  
  Out of curiosity, why does it have to be in one line? It's much less readable & maintainable that way.
  
  – Jeff Schaller♦
  Apr 4 at 10:30
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  I am passing this line to specialized software. Then according to the output of the command, I can trigger an alarm and if I make it on more than a single line, I need to write more complex logic. The idea is to check a specific directory where there should not be any files for more than 20 seconds, I want to trigger an alarm if the age of the oldest file is more than 30 seconds.
  
  – Georgе Stoyanov
  Apr 4 at 10:39
  
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  also I would be very happy if you have any ideas, how I can simplify my command for finding the age of the oldest file
  
  – Georgе Stoyanov
  Apr 4 at 10:41
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  ls -lt | tail -1 will give you the oldest file; you can parse out the date or go through the stat stuff without having to do a single line shell loop
  
  – mpez0
  Apr 4 at 20:06
  
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  @mpez0 this is exactly what I am doing, check my original post.
  
  – Georgе Stoyanov
  2 days ago
  

  
  
  
  

add a comment | 

I want to find the age of the oldest file in a certain directory or return 0 if there aren't any files in this directory. I also need a one-line command doing it. So far this is my command for finding the age in seconds of the oldest file in the directory:

expr $(($(date +%s) - $(stat -c %Y $(ls -lt /path/to/dir/ | tail -1 | awk 'print $NF'))))

The problem is that if there are no files it is returning the following error:

$ expr $(($(date +%s) - $(stat -c %Y $(ls -lt /path/to/dir/ | tail -1 | awk 'print $NF'))))
stat: cannot stat ‘0’: No such file or directory
-bash: 1554373460 - : syntax error: operand expected (error token is "- ")

So in this case I want the command to return just 0 and to suppress the error printout.

shell-script files directory

share|improve this question

asked Apr 4 at 10:26

Georgе StoyanovGeorgе Stoyanov

164421

expr $(($(date +%s) - $(stat -c %Y $(ls -lt /path/to/dir/ | tail -1 | awk 'print $NF'))))

$ expr $(($(date +%s) - $(stat -c %Y $(ls -lt /path/to/dir/ | tail -1 | awk 'print $NF'))))
stat: cannot stat ‘0’: No such file or directory
-bash: 1554373460 - : syntax error: operand expected (error token is "- ")

share|improve this question

asked Apr 4 at 10:26

Georgе StoyanovGeorgе Stoyanov

164421

share|improve this question

asked Apr 4 at 10:26

Georgе StoyanovGeorgе Stoyanov

164421

asked Apr 4 at 10:26

Georgе StoyanovGeorgе Stoyanov

164421

asked Apr 4 at 10:26

Georgе StoyanovGeorgе Stoyanov

164421

2 Answers
2

active

oldest

votes

4

If it must be one line:

stat -c %Y ./* 2>/dev/null | awk -v d="$(date +%s)" 'BEGIN m=d $0 < m m = $0 END print d - m'

• 
  stat -c %Y ./* 2>/dev/null print the timestamp of all files, ignoring errors (so no files results in no output)


• 
  

  With awk:

  
  
  
  • 
    -v d="$(date +%s)" save the current timestamp in a variable d
    
  
  
  • 
    BEGIN m=d initialize m to d
    
  
  
  • 
    $0 < m m = $0 keeping track of the minimum in m
    
  
  
  • 
    END print d - m print the difference.
  
  

share|improve this answer

edited Apr 4 at 12:19

Stéphane Chazelas

313k57593949

answered Apr 4 at 10:44

murumuru

37.2k589164

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  unfortunately, it does return 0 no matter if the directory is empty or it has more than one file
  
  – Georgе Stoyanov
  Apr 4 at 10:55
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  @George ah, oops, I inverted the check for min
  
  – muru
  Apr 4 at 11:03
  

  
  
  
  

add a comment | 

5

With zsh and perl:

perl -le 'print 0+-M $ARGV[0]' /path/to/dir/*(N-Om[1])

(add the D glob qualifier if you also want to consider hidden files (but not . nor ..)).

Note that for symlinks, that considers the modification time of the file it resolves to. Remove the - in the glob qualifiers to consider the modification time of the symlink instead (and use (lstat$ARGV[0] && -M _) in perl to get the age of the symlink).

That gives the age in days. Multiply by 86400 to get a number of seconds:

perl -le 'print 86400*-M $ARGV[0]' /path/to/dir/*(N-Om[1])

• 
  (N-Om[1]): glob qualifier:
  
  
  • 
    N: turns on nullglob for that glob. So if there's no file in the directory, expands to nothing causing perl's -M to return undef.
  
  
  • 
    -: causes next glob qualifiers to apply on the target of symlinks
  
  
  • 
    Om: reverse (capital) order by modification time (so from oldest to newest like ls -rt)
  
  
  • 
    [1]: select first matching file only
  
  


• 
  -M file: gets the age of the content of the file.


• 
  0+ or 86400* force a conversion to number (for the undef case).

share|improve this answer

edited Apr 4 at 15:38

answered Apr 4 at 12:18

Stéphane ChazelasStéphane Chazelas

313k57593949

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  I am getting just 0 as an output even though it should show me a couple of thousands of seconds, both commands actually gives me the same output and on another machine I am getting an error: -bash: syntax error near unexpected token '(', the one giving me an error is running a rather old version of perl: v5.16.3
  
  – Georgе Stoyanov
  Apr 4 at 14:39
  
  

  
  
  
  


• 
  
  
  

  
  2
  

  
  
  
  
  
  

  
  
  @GeorgеStoyanov, the syntax is for zsh, not bash.
  
  – Stéphane Chazelas
  Apr 4 at 15:37
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  I missed that part :) Thanks for the answer @Stephane
  
  – Georgе Stoyanov
  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
);



);

draft saved

draft discarded

Sign up or log in

StackExchange.ready(function ()
StackExchange.helpers.onClickDraftSave('#login-link');
);

Sign up using Google

Sign up using Facebook

Sign up using Email and Password

Post as a guest

Name

Email

Required, but never shown

StackExchange.ready(
function ()
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2funix.stackexchange.com%2fquestions%2f510472%2ffind-the-age-of-the-oldest-file-in-one-line-or-return-zero%23new-answer', 'question_page');

);

Post as a guest

Name

Email

Required, but never shown

4

If it must be one line:

stat -c %Y ./* 2>/dev/null | awk -v d="$(date +%s)" 'BEGIN m=d $0 < m m = $0 END print d - m'

• 
  stat -c %Y ./* 2>/dev/null print the timestamp of all files, ignoring errors (so no files results in no output)


• 
  

  With awk:

  
  
  
  • 
    -v d="$(date +%s)" save the current timestamp in a variable d
    
  
  
  • 
    BEGIN m=d initialize m to d
    
  
  
  • 
    $0 < m m = $0 keeping track of the minimum in m
    
  
  
  • 
    END print d - m print the difference.
  
  

share|improve this answer

edited Apr 4 at 12:19

Stéphane Chazelas

313k57593949

answered Apr 4 at 10:44

murumuru

37.2k589164

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  unfortunately, it does return 0 no matter if the directory is empty or it has more than one file
  
  – Georgе Stoyanov
  Apr 4 at 10:55
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  @George ah, oops, I inverted the check for min
  
  – muru
  Apr 4 at 11:03
  

  
  
  
  

add a comment | 

4

If it must be one line:

stat -c %Y ./* 2>/dev/null | awk -v d="$(date +%s)" 'BEGIN m=d $0 < m m = $0 END print d - m'

• 
  stat -c %Y ./* 2>/dev/null print the timestamp of all files, ignoring errors (so no files results in no output)


• 
  

  With awk:

  
  
  
  • 
    -v d="$(date +%s)" save the current timestamp in a variable d
    
  
  
  • 
    BEGIN m=d initialize m to d
    
  
  
  • 
    $0 < m m = $0 keeping track of the minimum in m
    
  
  
  • 
    END print d - m print the difference.
  
  

share|improve this answer

edited Apr 4 at 12:19

Stéphane Chazelas

313k57593949

answered Apr 4 at 10:44

murumuru

37.2k589164

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  unfortunately, it does return 0 no matter if the directory is empty or it has more than one file
  
  – Georgе Stoyanov
  Apr 4 at 10:55
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  @George ah, oops, I inverted the check for min
  
  – muru
  Apr 4 at 11:03
  

  
  
  
  

add a comment | 

If it must be one line:

stat -c %Y ./* 2>/dev/null | awk -v d="$(date +%s)" 'BEGIN m=d $0 < m m = $0 END print d - m'

• 
  stat -c %Y ./* 2>/dev/null print the timestamp of all files, ignoring errors (so no files results in no output)


• 
  

  With awk:

  
  
  
  • 
    -v d="$(date +%s)" save the current timestamp in a variable d
    
  
  
  • 
    BEGIN m=d initialize m to d
    
  
  
  • 
    $0 < m m = $0 keeping track of the minimum in m
    
  
  
  • 
    END print d - m print the difference.
  
  

share|improve this answer

edited Apr 4 at 12:19

Stéphane Chazelas

313k57593949

answered Apr 4 at 10:44

murumuru

37.2k589164

stat -c %Y ./* 2>/dev/null | awk -v d="$(date +%s)" 'BEGIN m=d $0 < m m = $0 END print d - m'

share|improve this answer

edited Apr 4 at 12:19

Stéphane Chazelas

313k57593949

answered Apr 4 at 10:44

murumuru

37.2k589164

edited Apr 4 at 12:19

Stéphane Chazelas

313k57593949

edited Apr 4 at 12:19

Stéphane Chazelas

313k57593949

answered Apr 4 at 10:44

murumuru

37.2k589164

answered Apr 4 at 10:44

murumuru

37.2k589164

5

With zsh and perl:

perl -le 'print 0+-M $ARGV[0]' /path/to/dir/*(N-Om[1])

(add the D glob qualifier if you also want to consider hidden files (but not . nor ..)).

Note that for symlinks, that considers the modification time of the file it resolves to. Remove the - in the glob qualifiers to consider the modification time of the symlink instead (and use (lstat$ARGV[0] && -M _) in perl to get the age of the symlink).

That gives the age in days. Multiply by 86400 to get a number of seconds:

perl -le 'print 86400*-M $ARGV[0]' /path/to/dir/*(N-Om[1])

• 
  (N-Om[1]): glob qualifier:
  
  
  • 
    N: turns on nullglob for that glob. So if there's no file in the directory, expands to nothing causing perl's -M to return undef.
  
  
  • 
    -: causes next glob qualifiers to apply on the target of symlinks
  
  
  • 
    Om: reverse (capital) order by modification time (so from oldest to newest like ls -rt)
  
  
  • 
    [1]: select first matching file only
  
  


• 
  -M file: gets the age of the content of the file.


• 
  0+ or 86400* force a conversion to number (for the undef case).

share|improve this answer

edited Apr 4 at 15:38

answered Apr 4 at 12:18

Stéphane ChazelasStéphane Chazelas

313k57593949

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  I am getting just 0 as an output even though it should show me a couple of thousands of seconds, both commands actually gives me the same output and on another machine I am getting an error: -bash: syntax error near unexpected token '(', the one giving me an error is running a rather old version of perl: v5.16.3
  
  – Georgе Stoyanov
  Apr 4 at 14:39
  
  

  
  
  
  


• 
  
  
  

  
  2
  

  
  
  
  
  
  

  
  
  @GeorgеStoyanov, the syntax is for zsh, not bash.
  
  – Stéphane Chazelas
  Apr 4 at 15:37
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  I missed that part :) Thanks for the answer @Stephane
  
  – Georgе Stoyanov
  2 days ago
  

  
  
  
  

add a comment | 

5

With zsh and perl:

perl -le 'print 0+-M $ARGV[0]' /path/to/dir/*(N-Om[1])

(add the D glob qualifier if you also want to consider hidden files (but not . nor ..)).

Note that for symlinks, that considers the modification time of the file it resolves to. Remove the - in the glob qualifiers to consider the modification time of the symlink instead (and use (lstat$ARGV[0] && -M _) in perl to get the age of the symlink).

That gives the age in days. Multiply by 86400 to get a number of seconds:

perl -le 'print 86400*-M $ARGV[0]' /path/to/dir/*(N-Om[1])

• 
  (N-Om[1]): glob qualifier:
  
  
  • 
    N: turns on nullglob for that glob. So if there's no file in the directory, expands to nothing causing perl's -M to return undef.
  
  
  • 
    -: causes next glob qualifiers to apply on the target of symlinks
  
  
  • 
    Om: reverse (capital) order by modification time (so from oldest to newest like ls -rt)
  
  
  • 
    [1]: select first matching file only
  
  


• 
  -M file: gets the age of the content of the file.


• 
  0+ or 86400* force a conversion to number (for the undef case).

share|improve this answer

edited Apr 4 at 15:38

answered Apr 4 at 12:18

Stéphane ChazelasStéphane Chazelas

313k57593949

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  I am getting just 0 as an output even though it should show me a couple of thousands of seconds, both commands actually gives me the same output and on another machine I am getting an error: -bash: syntax error near unexpected token '(', the one giving me an error is running a rather old version of perl: v5.16.3
  
  – Georgе Stoyanov
  Apr 4 at 14:39
  
  

  
  
  
  


• 
  
  
  

  
  2
  

  
  
  
  
  
  

  
  
  @GeorgеStoyanov, the syntax is for zsh, not bash.
  
  – Stéphane Chazelas
  Apr 4 at 15:37
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  I missed that part :) Thanks for the answer @Stephane
  
  – Georgе Stoyanov
  2 days ago
  

  
  
  
  

add a comment | 

With zsh and perl:

perl -le 'print 0+-M $ARGV[0]' /path/to/dir/*(N-Om[1])

(add the D glob qualifier if you also want to consider hidden files (but not . nor ..)).

Note that for symlinks, that considers the modification time of the file it resolves to. Remove the - in the glob qualifiers to consider the modification time of the symlink instead (and use (lstat$ARGV[0] && -M _) in perl to get the age of the symlink).

That gives the age in days. Multiply by 86400 to get a number of seconds:

perl -le 'print 86400*-M $ARGV[0]' /path/to/dir/*(N-Om[1])

• 
  (N-Om[1]): glob qualifier:
  
  
  • 
    N: turns on nullglob for that glob. So if there's no file in the directory, expands to nothing causing perl's -M to return undef.
  
  
  • 
    -: causes next glob qualifiers to apply on the target of symlinks
  
  
  • 
    Om: reverse (capital) order by modification time (so from oldest to newest like ls -rt)
  
  
  • 
    [1]: select first matching file only
  
  


• 
  -M file: gets the age of the content of the file.


• 
  0+ or 86400* force a conversion to number (for the undef case).

share|improve this answer

edited Apr 4 at 15:38

answered Apr 4 at 12:18

Stéphane ChazelasStéphane Chazelas

313k57593949

perl -le 'print 0+-M $ARGV[0]' /path/to/dir/*(N-Om[1])

perl -le 'print 86400*-M $ARGV[0]' /path/to/dir/*(N-Om[1])

share|improve this answer

edited Apr 4 at 15:38

answered Apr 4 at 12:18

Stéphane ChazelasStéphane Chazelas

313k57593949

answered Apr 4 at 12:18

Stéphane ChazelasStéphane Chazelas

313k57593949

answered Apr 4 at 12:18

Stéphane ChazelasStéphane Chazelas

313k57593949