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102 lines
2.3 KiB
102 lines
2.3 KiB
#!/bin/sh
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# NAME
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#
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# letter_freq.sh - analyze letter frequency in a string
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#
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# SYNOPSIS
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#
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# letter_freq.sh -f filename
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# letter_freq.sh "string to analyze"
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#
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# INSTALLATION
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#
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# Just copy this into a file called letter_freq.sh, and then:
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#
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# $ chmod +x ./letter_freq.sh
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#
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# CAVEATS
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#
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# Shell is terrible and Brennen is terrible at shell, so this
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# is doubly likely to contain traps for the unwary.
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#
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# AUTHORS
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#
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# https://mspsocial.net/@earthtopus
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# https://mastodon.social/@brennen
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# A function for squawking at the user with some helptext:
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print_usage () {
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cat <<END
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USAGE
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# Examine a string directly:
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$ ./letter_freq.sh "Quick zephyrs blow, vexing daft Jim."
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# Examine a string from a file:
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$ ./letter_freq.sh -f pangram.txt
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END
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}
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# Encapsulate the sort operation in a function for less cruft below:
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do_sort () {
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sort | uniq -c | sort -rn;
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}
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# The script really starts here.
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# First, we'll handle arguments, hackily. $1 is the first parameter to the
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# command, $2 is the second, and so on. There's a trap here - if you say
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# something like
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#
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# ./letter_freq.sh foo bar
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#
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# ...then $1 will be 'foo' and $2 will be 'bar'. To have an entire string with
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# spaces come in as the first param, use quotes like so:
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#
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# ./letter_freq.sh "foo bar"
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#
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# The same sort of thing applies all over the place. When in doubt, put double
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# quotes around variables to avoid weirdness.
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if [ "$1" = '-f' ]; then
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if [ -z "$2" ]; then
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# Zero-length string for second param - didn't get a filename
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echo "Expected a filename to read string from."
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print_usage
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# These arbitrary-seeming exit codes are taken from:
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# https://www.freebsd.org/cgi/man.cgi?query=sysexits&sektion=3
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# (I don't actually know whether this is a good idea.)
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exit 64
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fi
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if [ ! -f "$2" ]; then
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echo "No such file: $2"
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print_usage
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exit 64
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fi
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# Read the file into a variable:
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string=$(cat "$2")
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elif [ -z "$1" ]; then
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echo "Expected a string to analyze."
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print_usage
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exit 66
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else
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# Use the provided string:
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string="$1"
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fi
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# Next, we actually Do the Stuff:
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count=$(echo "$string" | tr -cd '[:alpha:]' | wc -m)
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echo "$count total chars"
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echo "$string" | grep -oE '[[:alpha:]]' | \
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tr '[:upper:]' '[:lower:]' | \
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do_sort | \
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awk -v count="$count" '{ print ($1 / count), $1, $2; }'
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# Success!
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exit 0
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