ORD and CHR a file in Bash

问题

I build ord and chr functions and they work just fine. But if I take a file that contains \n, for example:

hello
CHECK THIS HIT
YES

when I ord everything I don't get any new line values. Why is that? I'm writing in Bash.

Here is the code that I am using:

function ord { 
    ordr="`printf "%d\n" \'$1`" 
}

TEXT="`cat $1`"
for (( i=0; i<${#TEXT}; i++ )) 
do 
    ord "${TEXT:$i:1}" 
    echo "$ordr" 
done

回答1:

Your ord function is really weird. Maybe it would be better to write it as:

function ord { 
    printf -v ordr "%d" "'$1"
}

Then you would use it as:

TEXT=$(cat "$1")
for (( i=0; i<${#TEXT}; i++ )); do 
    ord "${TEXT:$i:1}" 
    printf '%s\n' "$ordr"
done

This still leaves two problems: you won't be able to have null bytes and you won't see trailing newlines. For example (I called your script banana and chmod +x banana):

$ ./banana <(printf 'a\0b\n')
97
98

Two problems show here: the null byte is removed from Bash in the TEXT=$(cat "$1") part, as a Bash variable can't contain null bytes. Moreover, this step also trims trailing newlines.

A more robust approach would be to use read:

while IFS= read -r -n 1 -d '' char; do
    ord "$char"
    printf '%s\n' "$ordr"
done < "$1"

With this modification:

$ ./banana <(printf 'a\0b\n')
97
0
98
10

Note that this script will depend on your locale. With my locale (LANG="en_US.UTF-8):

$ ./banana <(printf 'a\0ℂ\n')
97
0
8450
10

whereas:

$ LANG= ./banana <(printf 'a\0ℂ\n')
97
0
226
132
130
10

That's to show you that Bash doesn't read bytes, but characters. So depending on how you want Bash to treat your data, set LANG accordingly.

If your script only does that, it's much simpler to not use an ord function at all:

#!/bin/bash

while IFS= read -r -n 1 -d '' char; do
    printf '%d\n' "'$char"
done < "$1"

It's that simple!

来源：https://stackoverflow.com/questions/28476611/ord-and-chr-a-file-in-bash

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chr

ord