How to check size of a file using Bash

Question

I ve got a script that checks for 0-size  but I thought there must be an easier way to check for file sizes instead   I e  file txt is normally 100k  how to make a script check if it is less than 90k  including 0   and make it do wget a new copy because the file is corrupt in this case   What I m currently using     if   -n file txt   then  echo  everything is good  else  mail -s  file txt size is zero  please fix    myemail gmail com  lt   dev null    Grab wget as a fallback   wget -c https   www server org file txt -P  root tmp --output-document  root tmp file txt  mv -f  root tmp file txt  var www file txt fi

User · Answer

stat appears to do this with the fewest system calls     set debian-live-8 2 0-amd64-xfce-desktop iso    strace stat --format  s  1   wc     282    2795   27364    strace wc --bytes  1   wc     307    3063   29091    strace du --bytes  1   wc     437    4376   41955    strace find  1 -printf  s   wc     604    6061   64793

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alternative solution with awk and double parenthesis   FILENAME file txt SIZE   du -sb  FILENAME   awk    print  1      if   SIZE lt 90000     then      echo  less    else      echo  not less    fi

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-n file txt   doesn t check its size  it checks that the string file txt is non-zero length  so it will always succeed   If you want to say  size is non-zero   you need   -s file txt     To get a file s size  you can use wc -c to get the size  file length  in bytes   file file txt minimumsize 90000 actualsize   wc -c  lt   file   if    actualsize -ge  minimumsize    then     echo size is over  minimumsize bytes else     echo size is under  minimumsize bytes fi   In this case  it sounds like that s what you want   But FYI  if you want to know how much disk space the file is using  you could use du -k to get the size  disk space used  in kilobytes   file file txt minimumsize 90 actualsize   du -k   file    cut -f 1  if    actualsize -ge  minimumsize    then     echo size is over  minimumsize kilobytes else     echo size is under  minimumsize kilobytes fi   If you need more control over the output format  you can also look at stat   On Linux  you d start with something like stat -c   s  file txt  and on BSD Mac OS X  something like stat -f   z  file txt

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For getting the file size in both Linux and Mac OS X  and presumably other BSDs   there are not many options  and most of the ones suggested here will only work on one system   Given f  path to your file   what does work in both Linux and Mac s Bash   size    perl -e  print -s shift    f      or  size    wc -c   f    awk   print  1       The other answers work fine in Linux  but not in Mac    du doesn t have a -b option in Mac  and the BLOCKSIZE 1 trick doesn t work   minimum blocksize is 512   which leads to a wrong result  cut -d    -f1 doesn t work because on Mac  the number may be right-aligned  padded with spaces in front    So if you need something flexible  it s either perl s -s operator   or wc -c piped to awk   print  1    awk will ignore the leading white space    And of course  regarding the rest of your original question  use the -lt  or -gt  operator    if    size -lt  your wanted size    then etc

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ls -l  file   awk   print  6     assuming that ls command reports filesize at column  6

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python -c  import os  print  os path getsize      filename           portable  all flavours of python  avoids variation in stat dialects

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It surprises me that no one mentioned stat to check file size  Some methods are definitely better  using -s to find out whether the file is empty or not is easier than anything else if that s all you want  And if you want to find files of a size  then find is certainly the way to go   I also like du a lot to get file size in kb  but  for bytes  I d use stat   size   stat -f z  filename    BSD stat  size   stat -c s  filename    GNU stat

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Based on gniourf gniourf   s answer   find  file txt  -size -90k   will write file txt to stdout if and only if the size of file txt is less than 90K  and  find  file txt  -size -90k -exec command     will execute the command command if file txt has a size less than 90K    I have tested this on Linux    From find 1             Command-line arguments following  the -H  -L and -P options  are taken to be names of files or directories to be examined  up to the first argument that begins with    -            emphasis added

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If your find handles this syntax  you can use it   find -maxdepth 1 -name  file txt  -size -90k   This will output file txt to stdout if and only if the size of file txt is less than 90k  To execute a script script if file txt has a size less than 90k   find -maxdepth 1 -name  file txt  -size -90k -exec script

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I would use du s --threshold for this  Not sure if this option is available in all versions of du but it is implemented in GNU s version   Quoting from du 1  s manual   -t  --threshold SIZE        exclude entries smaller than SIZE if positive  or entries greater        than SIZE if negative   Here s my solution  using du --threshold  for OP s use case   THRESHOLD 90k if    -z    du --threshold   THRESHOLD  file txt       then     mail -s  file txt size is below   THRESHOLD   please fix    myemail gmail com  lt   dev null     mv -f  root tmp file txt  var www file txt fi   The advantage of that  is that du can accept an argument to that option in a known format - either human as in 10K  10MiB or what ever you feel comfortable with - you don t need to manually convert between formats   units since du handles that   For reference  here s the explanation on this SIZE argument from the man page   The SIZE argument is an integer and optional unit  example  10K is  10 1024   Units are K M G T P E Z Y  powers of 1024  or KB MB      powers of 1000   Binary prefixes can be used  too  KiB K  MiB M  and so on

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This works in both linux and macos  function filesize       local file  1     size  stat -c s  file 2 gt  dev null    linux     if      -eq 0       then         echo  size         return 0     fi      eval   stat -s  file    macos     if      -eq 0       then         echo  st size         return 0     fi      return -1

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If you are looking for just the size of a file     cat  file   wc -c  gt  203233

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Okay  if you re on a Mac  do this  stat -f  z   Users Example config log   That s it

[bash] How to check size of a file using Bash?

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