cat shows nothing












6















My team is working on a CI environment.



A ko file, named x.ko, is always generated from the CI environment at a regular time everyday and its type is ELF 64-bit LSB relocatable.



Today, I found that the type of this ko file became data.



I'm trying to figure out the reason.



I try to cat this ko file but the output is nothing. Then, I try to cat -et x.ko, and it gives me lots of ^@^@^@^@^@^@^@^@^@^@^@^@^@^@...



Do you know what ^@^@^@^@^@^@^@^@^@ means?






files cat file-types







share|improve this question


















  • 1





    ^@ .... that is a CTRL-@ ..... hold ctrl key and press @ ..... it is a NULL .... 0 byte

    – jsotola
    14 hours ago








  • 1





    It is corrupted. Has it crashed?

    – Rui F Ribeiro
    13 hours ago








  • 1





    You can use od to analyse binary data. However in this case, all the evidence suggests it is a lot of zero bytes (nulls).

    – ctrl-alt-delor
    10 hours ago
















6















My team is working on a CI environment.



A ko file, named x.ko, is always generated from the CI environment at a regular time everyday and its type is ELF 64-bit LSB relocatable.



Today, I found that the type of this ko file became data.



I'm trying to figure out the reason.



I try to cat this ko file but the output is nothing. Then, I try to cat -et x.ko, and it gives me lots of ^@^@^@^@^@^@^@^@^@^@^@^@^@^@...



Do you know what ^@^@^@^@^@^@^@^@^@ means?






files cat file-types







share|improve this question


















  • 1





    ^@ .... that is a CTRL-@ ..... hold ctrl key and press @ ..... it is a NULL .... 0 byte

    – jsotola
    14 hours ago








  • 1





    It is corrupted. Has it crashed?

    – Rui F Ribeiro
    13 hours ago








  • 1





    You can use od to analyse binary data. However in this case, all the evidence suggests it is a lot of zero bytes (nulls).

    – ctrl-alt-delor
    10 hours ago














6












6








6


2






My team is working on a CI environment.



A ko file, named x.ko, is always generated from the CI environment at a regular time everyday and its type is ELF 64-bit LSB relocatable.



Today, I found that the type of this ko file became data.



I'm trying to figure out the reason.



I try to cat this ko file but the output is nothing. Then, I try to cat -et x.ko, and it gives me lots of ^@^@^@^@^@^@^@^@^@^@^@^@^@^@...



Do you know what ^@^@^@^@^@^@^@^@^@ means?






files cat file-types







share|improve this question














My team is working on a CI environment.



A ko file, named x.ko, is always generated from the CI environment at a regular time everyday and its type is ELF 64-bit LSB relocatable.



Today, I found that the type of this ko file became data.



I'm trying to figure out the reason.



I try to cat this ko file but the output is nothing. Then, I try to cat -et x.ko, and it gives me lots of ^@^@^@^@^@^@^@^@^@^@^@^@^@^@...



Do you know what ^@^@^@^@^@^@^@^@^@ means?






files cat file-types




files cat file-types






share|improve this question













share|improve this question











share|improve this question




share|improve this question










asked 14 hours ago









YvesYves

917722




917722








  • 1





    ^@ .... that is a CTRL-@ ..... hold ctrl key and press @ ..... it is a NULL .... 0 byte

    – jsotola
    14 hours ago








  • 1





    It is corrupted. Has it crashed?

    – Rui F Ribeiro
    13 hours ago








  • 1





    You can use od to analyse binary data. However in this case, all the evidence suggests it is a lot of zero bytes (nulls).

    – ctrl-alt-delor
    10 hours ago














  • 1





    ^@ .... that is a CTRL-@ ..... hold ctrl key and press @ ..... it is a NULL .... 0 byte

    – jsotola
    14 hours ago








  • 1





    It is corrupted. Has it crashed?

    – Rui F Ribeiro
    13 hours ago








  • 1





    You can use od to analyse binary data. However in this case, all the evidence suggests it is a lot of zero bytes (nulls).

    – ctrl-alt-delor
    10 hours ago








1




1





^@ .... that is a CTRL-@ ..... hold ctrl key and press @ ..... it is a NULL .... 0 byte

– jsotola
14 hours ago







^@ .... that is a CTRL-@ ..... hold ctrl key and press @ ..... it is a NULL .... 0 byte

– jsotola
14 hours ago






1




1





It is corrupted. Has it crashed?

– Rui F Ribeiro
13 hours ago







It is corrupted. Has it crashed?

– Rui F Ribeiro
13 hours ago






1




1





You can use od to analyse binary data. However in this case, all the evidence suggests it is a lot of zero bytes (nulls).

– ctrl-alt-delor
10 hours ago





You can use od to analyse binary data. However in this case, all the evidence suggests it is a lot of zero bytes (nulls).

– ctrl-alt-delor
10 hours ago










2 Answers
2






active

oldest

votes


















11














Your file is full of nulls, rather than empty. A regular cat will print the nulls to standard output, but your terminal will generally display them each as nothing, while cat -v represents them as ^@. ^@ represents a null byte because the byte value of "@" (0x40, or 64) xor 64 (flip bit 7) is zero.



Why it's suddenly full of nulls, we can't tell from here.



This related question may be informative about the caret representation: Are ASCII escape sequences and control characters pairings part of a standard?






share|improve this answer
























  • M. Ribeiro is clearly thinking of unix.stackexchange.com/questions/477537 .

    – JdeBP
    3 hours ago



















11














be careful , cat is not the perfect tool to display data than can be binary .



A simple unix tool is od ( octal dump ) .



A example of od -c -tx1



root@server:~# od -c -tx1 /etc/passwd | head

0000000   r   o   o   t   :   x   :   0   :   0   :   r   o   o   t   :

         72  6f  6f  74  3a  78  3a  30  3a  30  3a  72  6f  6f  74  3a

0000020   /   r   o   o   t   :   /   b   i   n   /   b   a   s   h  n

         2f  72  6f  6f  74  3a  2f  62  69  6e  2f  62  61  73  68  0a

0000040   d   a   e   m   o   n   :   x   :   1   :   1   :   d   a   e

         64  61  65  6d  6f  6e  3a  78  3a  31  3a  31  3a  64  61  65

0000060   m   o   n   :   /   u   s   r   /   s   b   i   n   :   /   u

         6d  6f  6e  3a  2f  75  73  72  2f  73  62  69  6e  3a  2f  75

0000100   s   r   /   s   b   i   n   /   n   o   l   o   g   i   n  n

         73  72  2f  73  62  69  6e  2f  6e  6f  6c  6f  67  69  6e  0a


so you can see that the carriage return n






share|improve this answer























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    2 Answers
    2






    active

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    2 Answers
    2






    active

    oldest

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    active

    oldest

    votes






    active

    oldest

    votes









    11














    Your file is full of nulls, rather than empty. A regular cat will print the nulls to standard output, but your terminal will generally display them each as nothing, while cat -v represents them as ^@. ^@ represents a null byte because the byte value of "@" (0x40, or 64) xor 64 (flip bit 7) is zero.



    Why it's suddenly full of nulls, we can't tell from here.



    This related question may be informative about the caret representation: Are ASCII escape sequences and control characters pairings part of a standard?






    share|improve this answer
























    • M. Ribeiro is clearly thinking of unix.stackexchange.com/questions/477537 .

      – JdeBP
      3 hours ago
















    11














    Your file is full of nulls, rather than empty. A regular cat will print the nulls to standard output, but your terminal will generally display them each as nothing, while cat -v represents them as ^@. ^@ represents a null byte because the byte value of "@" (0x40, or 64) xor 64 (flip bit 7) is zero.



    Why it's suddenly full of nulls, we can't tell from here.



    This related question may be informative about the caret representation: Are ASCII escape sequences and control characters pairings part of a standard?






    share|improve this answer
























    • M. Ribeiro is clearly thinking of unix.stackexchange.com/questions/477537 .

      – JdeBP
      3 hours ago














    11












    11








    11







    Your file is full of nulls, rather than empty. A regular cat will print the nulls to standard output, but your terminal will generally display them each as nothing, while cat -v represents them as ^@. ^@ represents a null byte because the byte value of "@" (0x40, or 64) xor 64 (flip bit 7) is zero.



    Why it's suddenly full of nulls, we can't tell from here.



    This related question may be informative about the caret representation: Are ASCII escape sequences and control characters pairings part of a standard?






    share|improve this answer













    Your file is full of nulls, rather than empty. A regular cat will print the nulls to standard output, but your terminal will generally display them each as nothing, while cat -v represents them as ^@. ^@ represents a null byte because the byte value of "@" (0x40, or 64) xor 64 (flip bit 7) is zero.



    Why it's suddenly full of nulls, we can't tell from here.



    This related question may be informative about the caret representation: Are ASCII escape sequences and control characters pairings part of a standard?







    share|improve this answer












    share|improve this answer



    share|improve this answer










    answered 14 hours ago









    Michael HomerMichael Homer

    49.7k8134173




    49.7k8134173













    • M. Ribeiro is clearly thinking of unix.stackexchange.com/questions/477537 .

      – JdeBP
      3 hours ago



















    • M. Ribeiro is clearly thinking of unix.stackexchange.com/questions/477537 .

      – JdeBP
      3 hours ago

















    M. Ribeiro is clearly thinking of unix.stackexchange.com/questions/477537 .

    – JdeBP
    3 hours ago





    M. Ribeiro is clearly thinking of unix.stackexchange.com/questions/477537 .

    – JdeBP
    3 hours ago













    11














    be careful , cat is not the perfect tool to display data than can be binary .



    A simple unix tool is od ( octal dump ) .



    A example of od -c -tx1



    root@server:~# od -c -tx1 /etc/passwd | head
    
0000000   r   o   o   t   :   x   :   0   :   0   :   r   o   o   t   :
    
         72  6f  6f  74  3a  78  3a  30  3a  30  3a  72  6f  6f  74  3a
    
0000020   /   r   o   o   t   :   /   b   i   n   /   b   a   s   h  n
    
         2f  72  6f  6f  74  3a  2f  62  69  6e  2f  62  61  73  68  0a
    
0000040   d   a   e   m   o   n   :   x   :   1   :   1   :   d   a   e
    
         64  61  65  6d  6f  6e  3a  78  3a  31  3a  31  3a  64  61  65
    
0000060   m   o   n   :   /   u   s   r   /   s   b   i   n   :   /   u
    
         6d  6f  6e  3a  2f  75  73  72  2f  73  62  69  6e  3a  2f  75
    
0000100   s   r   /   s   b   i   n   /   n   o   l   o   g   i   n  n
    
         73  72  2f  73  62  69  6e  2f  6e  6f  6c  6f  67  69  6e  0a


    so you can see that the carriage return n






    share|improve this answer




























      11














      be careful , cat is not the perfect tool to display data than can be binary .



      A simple unix tool is od ( octal dump ) .



      A example of od -c -tx1



      root@server:~# od -c -tx1 /etc/passwd | head
      
0000000   r   o   o   t   :   x   :   0   :   0   :   r   o   o   t   :
      
         72  6f  6f  74  3a  78  3a  30  3a  30  3a  72  6f  6f  74  3a
      
0000020   /   r   o   o   t   :   /   b   i   n   /   b   a   s   h  n
      
         2f  72  6f  6f  74  3a  2f  62  69  6e  2f  62  61  73  68  0a
      
0000040   d   a   e   m   o   n   :   x   :   1   :   1   :   d   a   e
      
         64  61  65  6d  6f  6e  3a  78  3a  31  3a  31  3a  64  61  65
      
0000060   m   o   n   :   /   u   s   r   /   s   b   i   n   :   /   u
      
         6d  6f  6e  3a  2f  75  73  72  2f  73  62  69  6e  3a  2f  75
      
0000100   s   r   /   s   b   i   n   /   n   o   l   o   g   i   n  n
      
         73  72  2f  73  62  69  6e  2f  6e  6f  6c  6f  67  69  6e  0a


      so you can see that the carriage return n






      share|improve this answer


























        11












        11








        11







        be careful , cat is not the perfect tool to display data than can be binary .



        A simple unix tool is od ( octal dump ) .



        A example of od -c -tx1



        root@server:~# od -c -tx1 /etc/passwd | head
        
0000000   r   o   o   t   :   x   :   0   :   0   :   r   o   o   t   :
        
         72  6f  6f  74  3a  78  3a  30  3a  30  3a  72  6f  6f  74  3a
        
0000020   /   r   o   o   t   :   /   b   i   n   /   b   a   s   h  n
        
         2f  72  6f  6f  74  3a  2f  62  69  6e  2f  62  61  73  68  0a
        
0000040   d   a   e   m   o   n   :   x   :   1   :   1   :   d   a   e
        
         64  61  65  6d  6f  6e  3a  78  3a  31  3a  31  3a  64  61  65
        
0000060   m   o   n   :   /   u   s   r   /   s   b   i   n   :   /   u
        
         6d  6f  6e  3a  2f  75  73  72  2f  73  62  69  6e  3a  2f  75
        
0000100   s   r   /   s   b   i   n   /   n   o   l   o   g   i   n  n
        
         73  72  2f  73  62  69  6e  2f  6e  6f  6c  6f  67  69  6e  0a


        so you can see that the carriage return n






        share|improve this answer













        be careful , cat is not the perfect tool to display data than can be binary .



        A simple unix tool is od ( octal dump ) .



        A example of od -c -tx1



        root@server:~# od -c -tx1 /etc/passwd | head
        
0000000   r   o   o   t   :   x   :   0   :   0   :   r   o   o   t   :
        
         72  6f  6f  74  3a  78  3a  30  3a  30  3a  72  6f  6f  74  3a
        
0000020   /   r   o   o   t   :   /   b   i   n   /   b   a   s   h  n
        
         2f  72  6f  6f  74  3a  2f  62  69  6e  2f  62  61  73  68  0a
        
0000040   d   a   e   m   o   n   :   x   :   1   :   1   :   d   a   e
        
         64  61  65  6d  6f  6e  3a  78  3a  31  3a  31  3a  64  61  65
        
0000060   m   o   n   :   /   u   s   r   /   s   b   i   n   :   /   u
        
         6d  6f  6e  3a  2f  75  73  72  2f  73  62  69  6e  3a  2f  75
        
0000100   s   r   /   s   b   i   n   /   n   o   l   o   g   i   n  n
        
         73  72  2f  73  62  69  6e  2f  6e  6f  6c  6f  67  69  6e  0a


        so you can see that the carriage return n







        share|improve this answer












        share|improve this answer



        share|improve this answer










        answered 14 hours ago









        EchoMike444EchoMike444

        7004




        7004






























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