Python 3: secrets module
string module
$ python3
>>> import string
>>> dir(string)
['Formatter', 'Template', '_ChainMap', '_TemplateMetaclass', 'all', 'builtins', 'cached', 'doc', 'file', 'loader', 'name', 'package', 'spec', '_re', '_string', 'ascii_letters', 'ascii_lowercase', 'ascii_uppercase', 'capwords', 'digits', 'hexdigits', 'octdigits', 'printable', 'punctuation', 'whitespace']
>>> string.capwords('hello world')
'Hello World'
>>> string.ascii_letters
'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ'
>>> string.digits
'0123456789'
>>> string.punctuation
'!"#$%&\'()*+,-./:;<=>?@[\]^_`{|}~'
>>> string.whitespace
' \t\n\r\x0b\x0c'
>>> len(string.whitespace + string.digits + string.ascii_letters + string.punctuation)
100
>>> len(string.printable)
100secrets module
See: https://docs.python.org/3/library/secrets.html
>>> import secrets
>>> ''.join(secrets.choice(''.join(set(string.printable) - set(string.whitespace))) for i in range(32))
'\rg@P_Jb\WyRW[n$GVM(qjZoCfJ48*(d'
>>> alphabet = string.ascii_letters + string.digits
>>> while True:
… password = ''.join(secrets.choice(alphabet) for i in range(10))
… if (any(c.islower() for c in password)
… and any(c.isupper() for c in password)
… and sum(c.isdigit() for c in password) >= 3):
… break
>>> password
'N4Ur7yq99B'Random Strings for Bash
For macOS, add env LC_ALL=C to avoid error: tr: Illegal byte sequence
$ tr -cd "[:alnum:]" < /dev/urandom | head -c 12
boIqf8FNkXXj
$ tr -cd "[:lower:][:digit:]" < /dev/urandom | head -c 12
1jemmxwkoy2v
$ tr -cd "[:digit:]" < /dev/urandom | head -c 10
4392078854
$ env LC_ALL=C tr -cd "[:digit:][:upper:]" < /dev/urandom | head -c 20
50C7EUZGYR5AOPDZO7IO$ man tr
TR(1) BSD General Commands Manual TR(1)
NAME
tr -- translate characters
SYNOPSIS
tr [-Ccsu] string1 string2
tr [-Ccu] -d string1
tr [-Ccu] -s string1
tr [-Ccu] -ds string1 string2
DESCRIPTION
The tr utility copies the standard input to the standard output with substitution or deletion of
selected characters.
The following options are available:
-C Complement the set of characters in string1, that is ``-C ab'' includes every character except
for `a' and `b'.
-c Same as -C but complement the set of values in string1.
-d Delete characters in string1 from the input.
-s Squeeze multiple occurrences of the characters listed in the last operand (either string1 or
string2) in the input into a single instance of the character. This occurs after all deletion
and translation is completed.
-u Guarantee that any output is unbuffered.
In the first synopsis form, the characters in string1 are translated into the characters in string2
where the first character in string1 is translated into the first character in string2 and so on. If
string1 is longer than string2, the last character found in string2 is duplicated until string1 is
exhausted.
In the second synopsis form, the characters in string1 are deleted from the input.
In the third synopsis form, the characters in string1 are compressed as described for the -s option.
In the fourth synopsis form, the characters in string1 are deleted from the input, and the characters
in string2 are compressed as described for the -s option.
The following conventions can be used in string1 and string2 to specify sets of characters:
character Any character not described by one of the following conventions represents itself.
\octal A backslash followed by 1, 2 or 3 octal digits represents a character with that encoded
value. To follow an octal sequence with a digit as a character, left zero-pad the octal
sequence to the full 3 octal digits.
\character
A backslash followed by certain special characters maps to special values.
\a <alert character>
\b <backspace>
\f <form-feed>
\n <newline>
\r <carriage return>
\t <tab>
\v <vertical tab>
A backslash followed by any other character maps to that character.
c-c For non-octal range endpoints represents the range of characters between the range end-
points, inclusive, in ascending order, as defined by the collation sequence. If either or
both of the range endpoints are octal sequences, it represents the range of specific coded
values between the range endpoints, inclusive.
...
[:class:] Represents all characters belonging to the defined character class. Class names are:
alnum <alphanumeric characters>
alpha <alphabetic characters>
blank <whitespace characters>
cntrl <control characters>
digit <numeric characters>
graph <graphic characters>
ideogram <ideographic characters>
lower <lower-case alphabetic characters>
phonogram <phonographic characters>
print <printable characters>
punct <punctuation characters>
rune <valid characters>
space <space characters>
special <special characters>
upper <upper-case characters>
xdigit <hexadecimal characters>
When ``[:lower:]'' appears in string1 and ``[:upper:]'' appears in the same relative posi-
tion in string2, it represents the characters pairs from the toupper mapping in the LC_CTYPE
category of the current locale. When ``[:upper:]'' appears in string1 and ``[:lower:]''
appears in the same relative position in string2, it represents the characters pairs from
the tolower mapping in the LC_CTYPE category of the current locale.
With the exception of case conversion, characters in the classes are in unspecified order.
For specific information as to which ASCII characters are included in these classes, see
ctype(3) and related manual pages.
[=equiv=] Represents all characters belonging to the same equivalence class as equiv, ordered by their
encoded values.
[#*n] Represents n repeated occurrences of the character represented by #. This expression is
only valid when it occurs in string2. If n is omitted or is zero, it is be interpreted as
large enough to extend string2 sequence to the length of string1. If n has a leading zero,
it is interpreted as an octal value, otherwise, it is interpreted as a decimal value.
ENVIRONMENT
The LANG, LC_ALL, LC_CTYPE and LC_COLLATE environment variables affect the execution of tr as described
in environ(7).
EXIT STATUS
The tr utility exits 0 on success, and >0 if an error occurs.
EXAMPLES
The following examples are shown as given to the shell:
Create a list of the words in file1, one per line, where a word is taken to be a maximal string of let-
ters.
tr -cs "[:alpha:]" "\n" > file1
Translate the contents of file1 to upper-case.
tr "[:lower:]" "[:upper:]" > file1
(This should be preferred over the traditional UNIX idiom of ``tr a-z A-Z'', since it works correctly
in all locales.)
Strip out non-printable characters from file1.
tr -cd "[:print:]" > file1
Remove diacritical marks from all accented variants of the letter `e':
tr "[=e=]" "e"
Example
$ tldr tr
tr
Translate characters: run replacements based on single characters and character sets.
- Replace all occurrences of a character in a file, and print the result:
tr find_character replace_character < filename
- Replace all occurrences of a character from another command's output:
echo text | tr find_character replace_character
- Map each character of the first set to the corresponding character of the second set:
tr 'abcd' 'jkmn' < filename
- Delete all occurrences of the specified set of characters from the input:
tr -d 'input_characters' < filename
- Compress a series of identical characters to a single character:
tr -s 'input_characters' < filename
- Translate the contents of a file to upper-case:
tr "[:lower:]" "[:upper:]" < filename
- Strip out non-printable characters from a file:
tr -cd "[:print:]" < filenameStrong Password with tr and /dev/urandom
For macOS, add env LC_ALL=C to avoid error: tr: Illegal byte sequence
$ tr -cd "[:print:]" < /dev/urandom | tr -d "[:blank:]" | head -c 32
m5.egq+[7bEb_\B|Iv`9}zftF>^i\O=
$ env LC_ALL=C tr -cd "[:print:]" < /dev/urandom | tr -d "[:blank:]" | head -c 32
NST5$^X72F2q~-&a#Q)?$HeO%sv'vWvD$ pwgen -sync 32 1
Q{:5\D%S8{I!O_h<G-\Hgh)9a=}H71zh$ pwgen -h
Usage: pwgen [ OPTIONS ] [ pw_length ] [ num_pw ]
Options supported by pwgen:
-c or --capitalize
Include at least one capital letter in the password
-A or --no-capitalize
Don't include capital letters in the password
-n or --numerals
Include at least one number in the password
-0 or --no-numerals
Don't include numbers in the password
-y or --symbols
Include at least one special symbol in the password
-r or --remove-chars=
Remove characters from the set of characters to generate passwords
-s or --secure
Generate completely random passwords
-B or --ambiguous
Don't include ambiguous characters in the password
-h or --help
Print a help message
-H or --sha1=path/to/file[#seed]
Use sha1 hash of given file as a (not so) random generator
-C
Print the generated passwords in columns
-1
Don't print the generated passwords in columns
-v or --no-vowels
Do not use any vowels so as to avoid accidental nasty words