====== Check files for holes ======


It's quite hard to tell if a file under Linux has holes (eg. it is a [[wp>sparse file]]). This script tries to determine this by comparing apparent and real file sizes.

<code bash>
#!/bin/sh

where=${1:-.}

find "$where" -type f | while read file; do

#    apparentsize=`du --apparent-size "$file" | cut -f 1`
#    realsize=`du "$file" | cut -f 1`

    blocks=`stat -c "%b" "$file"`
    blocksize=`stat -c "%B" "$file"`
    realsize=$(($blocks * $blocksize))
    apparentsize=`stat -c "%s" "$file"`

    diff=$(($apparentsize < $realsize))

    if [ $diff -eq 0 ]; then
        echo [has holes?] $file [real:${realsize} apparent:${apparentsize}]
        hole='found'
    fi

done

if [ -z $hole ]; then

    echo "no hole candidates found"

fi
</code>

{{tag>util files hole sparse bash}}

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