69 lines
2.1 KiB
Bash
Executable file
69 lines
2.1 KiB
Bash
Executable file
#!/bin/bash
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# ERROR: /bin/bash -w is invalid option is the error message here. Unable to find answer to problem at this time.
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# Keeping this file for learning purposes.
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# bestcompress--Given a file, tries compressing it with all the available
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# compression tools and keeps the compressed file that's smallest,
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# reporting the result to the user. If -a isn't specified, bestcompress
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# skips compressed files in the input stream.
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Z="compress" gz="gzip" bz="bzip2"
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Zout="/tmp/bestcompress.$$.Z"
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gzout="/tmp/bestcompress.$$.gz"
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bzout="/tmp/bestcompress.$$.bz"
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skipcompressed=1
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if [ "$1" = "-a" ] ; then
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skipcompressed=0 ; shift
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fi
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if [ $# -eq 0 ] ; then
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echo "Usage: $0 [-a] file or files to optimally compress" >&2
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exit 1
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fi
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trap "/bin/rm -f $Zout $gzout $bzout" EXIT
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for name in "$@"
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do
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if [ ! -f "$name" ] ; then
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echo "$0: file $name not found. Skipped." >&2
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continue
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fi
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if [ "$(echo $name | egrep '(\.Z$|\.gz$|\.bz2$)')" != "" ] ; then
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if [ $skipcompressed -eq 1 ] ; then
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echo "Skipped file ${name}: It's already compressed."
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continue
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else
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echo "Warning: Trying to double-compress $name"
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fi
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fi
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# Try compressing all three files in parallel.
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$Z < "$name" > $Zout &
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$gz < "$name" > $gzout &
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$bz < "$name" > $bzout &
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wait # Wait until all compressions are done.
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# Figure out which compressed best.
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smallest="$(ls -l "$name" $Zout $gzout $bzout | \parallel
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awk '{print $5"="NR}' | sort -n | cut -d= -f2 | head -1)"
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case "$smallest" in
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1 ) echo "No space savings by compressing $name. Left as is."
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;;
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2 ) echo Best compression is with compress. File renamed ${name}.Zout
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mv $Zout "${name}.Z" ; rm -f "$name"
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;;
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3 ) echo Best compression is with gzip. File renamed ${name}.gz
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mv $gzout "${name}.gz" ; rm -f "$name"
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;;
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4 ) echo Best compression is with bzip2. File renamed ${name}.bz2
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mv $bzout "${name}.bz2" ; rm -f "$name"
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esac
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done
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exit 0
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