Separate numbers, strings from one line using bash

Question

How to separate strings and numbers from one line using a bash command.

Example: I have a string containing

string123anotherstr456thenanotherstr789

The output should be:

string
123
anotherstr
456
thenanotherstr
789

Solution 1

GNU grep or compatible solution:

s="string123anotherstr456thenanotherstr789"
grep -Eo '[[:alpha:]]+|[0-9]+' <<<"$s"

• [[:alpha:]]+|[0-9]+ - regex alternation group, matches either alphabetic character(s) or number(s); both will be considered as separate entries on output

The output:

string
123
anotherstr
456
thenanotherstr
789

Solution 2

POSIXly:

string=string123anotherstr456thenanotherstr789
sed '
  s/[^[:alnum:]]//g; # remove anything other than letters and numbers
  s/[[:alpha:]]\{1,\}/&\
/g; # insert a newline after each sequence of letters
  s/[0-9]\{1,\}/&\
/g; # same for digits
  s/\n$//; # remove a trailing newline if any' << EOF
$string
EOF

Solution 3

GNU sed (or compatible) solution:

s="string123anotherstr456thenanotherstr789"
sed 's/[a-zA-Z]*\|[0-9]*/&\n/g; s/\n$//' <<<"$s"

The output:

string
123
anotherstr
456
thenanotherstr
789

Solution 4

python3

python3 -c '
from itertools import groupby
s = ("".join(g) for k, g in 
    groupby("string123anotherstr456thenanotherstr789", lambda x: x.isalpha()))
print(*s, sep="\n")
'

string
123
anotherstr
456
thenanotherstr
789

Solution 5

Used below one liner to achieve the same. As tested its worked fine

sed "s/[0-9]\{3\}/\n&/g" filename | sed "s/[0-9]\{3\}/&\n/g"| sed '/^$/d'

output

string
123
anotherstr
456
thenanotherstr
789

View more solutions

Comments

[G-Man Says 'Reinstate Monica']

@wjandrea:  The OP says (in a comment) “consider it is in a file”.

[G-Man Says 'Reinstate Monica']

It seems to me that you might as well say that the answer is printf 'string\n123\nanotherstr\n456\nthenanotherstr\n789\n'. I admit that the question is unclear, in the sense that it is incomplete, but the string presented in the question is clearly labeled as an example. I see no reason to assume that every number that will ever be in the input will be a three-digit number.

[G-Man Says 'Reinstate Monica']

(1) Gotcha!  (2) Why do you believe that the OP wants non-alphanumeric characters to be ignored?

[Stéphane Chazelas]

@G-Man, no good reason other than that's what the accepted answer does. It still differs from the accepted answer in that it will print an empty line for each line of input that contains neither letters nor digits.

[ilkkachu]

I think you could combine the first two seds and add both newlines at one go s/.../\n&\n/g. I also don't see why insist on the numbers being exactly three digits long, since it's trivial to make a more general solution.

[G-Man Says 'Reinstate Monica']

An additional (IMHO, more significant) difference: the accepted answer treats non-alphanumeric characters as word separators, and then discards them, so 3.14 becomes two output lines (3 and 14) and G-Man@stack becomes three (G, Man and stack). Your answer ignores them, so those inputs yield one output each (314 and GManstack).