Generate random text file in terminal

Question

I am trying to generate a random text file on my macbook from terminal. What I am trying is that:

tr -dc A-Za-z0-9 < /dev/urandom | head -c100 > RandomFile.txt

but im getting

tr: Illegal byte sequence

What am i doing wrong?

/dev/urandom delivers hex bytes in the range 00..ff. Start with hexdump /dev/urandom and check the manpage for hexdump's format options of it's output. — ott--
– ott--, Commented Nov 24, 2012 at 13:46

Michael Dautermann · Accepted Answer · 2012-11-24 13:48:10Z

9

Set this environment variable and you should be good to go:

setenv LC_ALL C

The answer for which I found on this page.

And with that environment variable in place, I see a nicely formatted output:

tr -dc A-Za-z0-9 < /dev/urandom | head -c100
Kk4kfjR3O0UraMpfTGicGvYCziFClJQUTO3zCXdo05RTxEUigqPXTkjtiGOsTsaNyqNR3rX2dsmPlHkSdqO5qWBTmIFIYezsekWT[~]:;

answered Nov 24, 2012 at 13:48

Michael Dautermann

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2 Comments

TheBlackCorsair Over a year ago

thanks, the page is useful. it is actually export LC_ALL=C instead of setenv LC_ALL C

Michael Dautermann Over a year ago

Yep. It depends on whatever shell your Terminal is using.

ormaaj · Accepted Answer · 2012-11-24 14:33:23Z

2

# Print or assign a random alphanumeric string of a given length.
# rndstr len [ var ]
function rndstr {
    if [[ $FUNCNAME == "${FUNCNAME[1]}" ]]; then
        unset -v a
        printf "$@"
    elif [[ $1 != +([[:digit:]]) ]]; then
        return 1
    elif (( ! $1 )); then
        return
    else
        typeset -a a=({a..z} {A..Z} {0..9})
        eval '${2:+"$FUNCNAME" -v} "${2:-printf}" -- %s "${a[RANDOM%'"${#a[@]}"']"{1..'"$1"'}"}"'
    fi
}

rndstr 100

This is my library function for this. The advantage is performance and the ability to assign to a variable directly. Might be overkill for you.

answered Nov 24, 2012 at 14:33

ormaaj

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