[bash] How do I split a string on a delimiter in Bash?

I have this string stored in a variable:

IN="[email protected];[email protected]"

Now I would like to split the strings by ; delimiter so that I have:

ADDR1="[email protected]"
ADDR2="[email protected]"

I don't necessarily need the ADDR1 and ADDR2 variables. If they are elements of an array that's even better.

After suggestions from the answers below, I ended up with the following which is what I was after:

#!/usr/bin/env bash

IN="[email protected];[email protected]"

mails=$(echo $IN | tr ";" "\n")

for addr in $mails
do
    echo "> [$addr]"
done

Output:

> [[email protected]]
> [[email protected]]

There was a solution involving setting Internal_field_separator (IFS) to ;. I am not sure what happened with that answer, how do you reset IFS back to default?

RE: IFS solution, I tried this and it works, I keep the old IFS and then restore it:

IN="[email protected];[email protected]"

OIFS=$IFS
IFS=';'
mails2=$IN
for x in $mails2
do
    echo "> [$x]"
done

IFS=$OIFS

BTW, when I tried

mails2=($IN)

I only got the first string when printing it in loop, without brackets around $IN it works.

Apart from the fantastic answers that were already provided, if it is just a matter of printing out the data you may consider using awk:

awk -F";" '{for (i=1;i<=NF;i++) printf("> [%s]\n", $i)}' <<< "$IN"

This sets the field separator to ;, so that it can loop through the fields with a for loop and print accordingly.

Test

$ IN="[email protected];[email protected]"
$ awk -F";" '{for (i=1;i<=NF;i++) printf("> [%s]\n", $i)}' <<< "$IN"
> [[email protected]]
> [[email protected]]

With another input:

$ awk -F";" '{for (i=1;i<=NF;i++) printf("> [%s]\n", $i)}' <<< "a;b;c   d;e_;f"
> [a]
> [b]
> [c   d]
> [e_]
> [f]

This is the simplest way to do it.

spo='one;two;three'
OIFS=$IFS
IFS=';'
spo_array=($spo)
IFS=$OIFS
echo ${spo_array[*]}

Taken from Bash shell script split array:

IN="[email protected];[email protected]"
arrIN=(${IN//;/ })
echo ${arrIN[1]}                  # Output: [email protected]

Explanation:

This construction replaces all occurrences of ';' (the initial // means global replace) in the string IN with ' ' (a single space), then interprets the space-delimited string as an array (that's what the surrounding parentheses do).

The syntax used inside of the curly braces to replace each ';' character with a ' ' character is called Parameter Expansion.

There are some common gotchas:

1. If the original string has spaces, you will need to use IFS:

• IFS=':'; arrIN=($IN); unset IFS;

2. If the original string has spaces and the delimiter is a new line, you can set IFS with:

• IFS=$'\n'; arrIN=($IN); unset IFS;

Without setting the IFS

If you just have one colon you can do that:

a="foo:bar"
b=${a%:*}
c=${a##*:}

you will get:

b = foo
c = bar

you can apply awk to many situations

echo "[email protected];[email protected]"|awk -F';' '{printf "%s\n%s\n", $1, $2}'

also you can use this

echo "[email protected];[email protected]"|awk -F';' '{print $1,$2}' OFS="\n"

Compatible answer

There are a lot of different ways to do this in bash.

However, it's important to first note that bash has many special features (so-called bashisms) that won't work in any other shell.

In particular, arrays, associative arrays, and pattern substitution, which are used in the solutions in this post as well as others in the thread, are bashisms and may not work under other shells that many people use.

For instance: on my Debian GNU/Linux, there is a standard shell called dash; I know many people who like to use another shell called ksh; and there is also a special tool called busybox with his own shell interpreter (ash).

Requested string

The string to be split in the above question is:

IN="[email protected];[email protected]"

I will use a modified version of this string to ensure that my solution is robust to strings containing whitespace, which could break other solutions:

IN="[email protected];[email protected];Full Name <[email protected]>"

Split string based on delimiter in bash (version >=4.2)

In pure bash, we can create an array with elements split by a temporary value for IFS (the input field separator). The IFS, among other things, tells bash which character(s) it should treat as a delimiter between elements when defining an array:

IN="[email protected];[email protected];Full Name <[email protected]>"

# save original IFS value so we can restore it later
oIFS="$IFS"
IFS=";"
declare -a fields=($IN)
IFS="$oIFS"
unset oIFS

In newer versions of bash, prefixing a command with an IFS definition changes the IFS for that command only and resets it to the previous value immediately afterwards. This means we can do the above in just one line:

IFS=\; read -a fields <<<"$IN"
# after this command, the IFS resets back to its previous value (here, the default):
set | grep ^IFS=
# IFS=$' \t\n'

We can see that the string IN has been stored into an array named fields, split on the semicolons:

set | grep ^fields=\\\|^IN=
# fields=([0]="[email protected]" [1]="[email protected]" [2]="Full Name <[email protected]>")
# IN='[email protected];[email protected];Full Name <[email protected]>'

(We can also display the contents of these variables using declare -p:)

declare -p IN fields
# declare -- IN="[email protected];[email protected];Full Name <[email protected]>"
# declare -a fields=([0]="[email protected]" [1]="[email protected]" [2]="Full Name <[email protected]>")

Note that read is the quickest way to do the split because there are no forks or external resources called.

Once the array is defined, you can use a simple loop to process each field (or, rather, each element in the array you've now defined):

# `"${fields[@]}"` expands to return every element of `fields` array as a separate argument
for x in "${fields[@]}" ;do
    echo "> [$x]"
    done
# > [[email protected]]
# > [[email protected]]
# > [Full Name <[email protected]>]

Or you could drop each field from the array after processing using a shifting approach, which I like:

while [ "$fields" ] ;do
    echo "> [$fields]"
    # slice the array 
    fields=("${fields[@]:1}")
    done
# > [[email protected]]
# > [[email protected]]
# > [Full Name <[email protected]>]

And if you just want a simple printout of the array, you don't even need to loop over it:

printf "> [%s]\n" "${fields[@]}"
# > [[email protected]]
# > [[email protected]]
# > [Full Name <[email protected]>]

Update: recent bash >= 4.4

In newer versions of bash, you can also play with the command mapfile:

mapfile -td \; fields < <(printf "%s\0" "$IN")

This syntax preserve special chars, newlines and empty fields!

If you don't want to include empty fields, you could do the following:

mapfile -td \; fields <<<"$IN"
fields=("${fields[@]%$'\n'}")   # drop '\n' added by '<<<'

With mapfile, you can also skip declaring an array and implicitly "loop" over the delimited elements, calling a function on each:

myPubliMail() {
    printf "Seq: %6d: Sending mail to '%s'..." $1 "$2"
    # mail -s "This is not a spam..." "$2" </path/to/body
    printf "\e[3D, done.\n"
}

mapfile < <(printf "%s\0" "$IN") -td \; -c 1 -C myPubliMail

(Note: the \0 at end of the format string is useless if you don't care about empty fields at end of the string or they're not present.)

mapfile < <(echo -n "$IN") -td \; -c 1 -C myPubliMail

# Seq:      0: Sending mail to '[email protected]', done.
# Seq:      1: Sending mail to '[email protected]', done.
# Seq:      2: Sending mail to 'Full Name <[email protected]>', done.

Or you could use <<<, and in the function body include some processing to drop the newline it adds:

myPubliMail() {
    local seq=$1 dest="${2%$'\n'}"
    printf "Seq: %6d: Sending mail to '%s'..." $seq "$dest"
    # mail -s "This is not a spam..." "$dest" </path/to/body
    printf "\e[3D, done.\n"
}

mapfile <<<"$IN" -td \; -c 1 -C myPubliMail

# Renders the same output:
# Seq:      0: Sending mail to '[email protected]', done.
# Seq:      1: Sending mail to '[email protected]', done.
# Seq:      2: Sending mail to 'Full Name <[email protected]>', done.

Split string based on delimiter in shell

If you can't use bash, or if you want to write something that can be used in many different shells, you often can't use bashisms -- and this includes the arrays we've been using in the solutions above.

However, we don't need to use arrays to loop over "elements" of a string. There is a syntax used in many shells for deleting substrings of a string from the first or last occurrence of a pattern. Note that * is a wildcard that stands for zero or more characters:

(The lack of this approach in any solution posted so far is the main reason I'm writing this answer ;)

${var#*SubStr}  # drops substring from start of string up to first occurrence of `SubStr`
${var##*SubStr} # drops substring from start of string up to last occurrence of `SubStr`
${var%SubStr*}  # drops substring from last occurrence of `SubStr` to end of string
${var%%SubStr*} # drops substring from first occurrence of `SubStr` to end of string

As explained by Score_Under:

# and % delete the shortest possible matching substring from the start and end of the string respectively, and

## and %% delete the longest possible matching substring.

Using the above syntax, we can create an approach where we extract substring "elements" from the string by deleting the substrings up to or after the delimiter.

The codeblock below works well in bash (including Mac OS's bash), dash, ksh, and busybox's ash:

IN="[email protected];[email protected];Full Name <[email protected]>"
while [ "$IN" ] ;do
    # extract the substring from start of string up to delimiter.
    # this is the first "element" of the string.
    iter=${IN%%;*}
    echo "> [$iter]"
    # if there's only one element left, set `IN` to an empty string.
    # this causes us to exit this `while` loop.
    # else, we delete the first "element" of the string from IN, and move onto the next.
    [ "$IN" = "$iter" ] && \
        IN='' || \
        IN="${IN#*;}"
  done
# > [[email protected]]
# > [[email protected]]
# > [Full Name <[email protected]>]

Have fun!

How about this one liner, if you're not using arrays:

IFS=';' read ADDR1 ADDR2 <<<$IN

The following Bash/zsh function splits its first argument on the delimiter given by the second argument:

split() {
    local string="$1"
    local delimiter="$2"
    if [ -n "$string" ]; then
        local part
        while read -d "$delimiter" part; do
            echo $part
        done <<< "$string"
        echo $part
    fi
}

For instance, the command

$ split 'a;b;c' ';'

yields

a
b
c

This output may, for instance, be piped to other commands. Example:

$ split 'a;b;c' ';' | cat -n
1   a
2   b
3   c

Compared to the other solutions given, this one has the following advantages:

• IFS is not overriden: Due to dynamic scoping of even local variables, overriding IFS over a loop causes the new value to leak into function calls performed from within the loop.

• Arrays are not used: Reading a string into an array using read requires the flag -a in Bash and -A in zsh.

If desired, the function may be put into a script as follows:

#!/usr/bin/env bash

split() {
    # ...
}

split "$@"

How about this approach:

IN="[email protected];[email protected]" 
set -- "$IN" 
IFS=";"; declare -a Array=($*) 
echo "${Array[@]}" 
echo "${Array[0]}" 
echo "${Array[1]}" 

Source

This also works:

IN="[email protected];[email protected]"
echo ADD1=`echo $IN | cut -d \; -f 1`
echo ADD2=`echo $IN | cut -d \; -f 2`

Be careful, this solution is not always correct. In case you pass "[email protected]" only, it will assign it to both ADD1 and ADD2.

There are two simple methods:

cat "text1;text2;text3" | tr " " "\n"

and

cat "text1;text2;text3" | sed -e 's/ /\n/g'

Maybe not the most elegant solution, but works with * and spaces:

IN="bla@so me.com;*;[email protected]"
for i in `delims=${IN//[^;]}; seq 1 $((${#delims} + 1))`
do
   echo "> [`echo $IN | cut -d';' -f$i`]"
done

Outputs

> [bla@so me.com]
> [*]
> [[email protected]]

Other example (delimiters at beginning and end):

IN=";bla@so me.com;*;[email protected];"
> []
> [bla@so me.com]
> [*]
> [[email protected]]
> []

Basically it removes every character other than ; making delims eg. ;;;. Then it does for loop from 1 to number-of-delimiters as counted by ${#delims}. The final step is to safely get the $ith part using cut.

IN='[email protected];[email protected];Charlie Brown <[email protected];!"#$%&/()[]{}*? are no problem;simple is beautiful :-)'
set -f
oldifs="$IFS"
IFS=';'; arrayIN=($IN)
IFS="$oldifs"
for i in "${arrayIN[@]}"; do
echo "$i"
done
set +f

Output:

[email protected]
[email protected]
Charlie Brown <[email protected]
!"#$%&/()[]{}*? are no problem
simple is beautiful :-)

Explanation: Simple assignment using parenthesis () converts semicolon separated list into an array provided you have correct IFS while doing that. Standard FOR loop handles individual items in that array as usual. Notice that the list given for IN variable must be "hard" quoted, that is, with single ticks.

IFS must be saved and restored since Bash does not treat an assignment the same way as a command. An alternate workaround is to wrap the assignment inside a function and call that function with a modified IFS. In that case separate saving/restoring of IFS is not needed. Thanks for "Bize" for pointing that out.

echo "[email protected];[email protected]" | sed -e 's/;/\n/g'
[email protected]
[email protected]

If no space, Why not this?

IN="[email protected];[email protected]"
arr=(`echo $IN | tr ';' ' '`)

echo ${arr[0]}
echo ${arr[1]}

Use the set built-in to load up the $@ array:

IN="[email protected];[email protected]"
IFS=';'; set $IN; IFS=$' \t\n'

Then, let the party begin:

echo $#
for a; do echo $a; done
ADDR1=$1 ADDR2=$2

Okay guys!

Here's my answer!

DELIMITER_VAL='='

read -d '' F_ABOUT_DISTRO_R <<"EOF"
DISTRIB_ID=Ubuntu
DISTRIB_RELEASE=14.04
DISTRIB_CODENAME=trusty
DISTRIB_DESCRIPTION="Ubuntu 14.04.4 LTS"
NAME="Ubuntu"
VERSION="14.04.4 LTS, Trusty Tahr"
ID=ubuntu
ID_LIKE=debian
PRETTY_NAME="Ubuntu 14.04.4 LTS"
VERSION_ID="14.04"
HOME_URL="http://www.ubuntu.com/"
SUPPORT_URL="http://help.ubuntu.com/"
BUG_REPORT_URL="http://bugs.launchpad.net/ubuntu/"
EOF

SPLIT_NOW=$(awk -F$DELIMITER_VAL '{for(i=1;i<=NF;i++){printf "%s\n", $i}}' <<<"${F_ABOUT_DISTRO_R}")
while read -r line; do
   SPLIT+=("$line")
done <<< "$SPLIT_NOW"
for i in "${SPLIT[@]}"; do
    echo "$i"
done

Why this approach is "the best" for me?

Because of two reasons:

1. You do not need to escape the delimiter;
2. You will not have problem with blank spaces. The value will be properly separated in the array!

[]'s

Here is a clean 3-liner:

in="foo@bar;bizz@buzz;fizz@buzz;buzz@woof"
IFS=';' list=($in)
for item in "${list[@]}"; do echo $item; done

where IFS delimit words based on the separator and () is used to create an array. Then [@] is used to return each item as a separate word.

If you've any code after that, you also need to restore $IFS, e.g. unset IFS.

I've seen a couple of answers referencing the cut command, but they've all been deleted. It's a little odd that nobody has elaborated on that, because I think it's one of the more useful commands for doing this type of thing, especially for parsing delimited log files.

In the case of splitting this specific example into a bash script array, tr is probably more efficient, but cut can be used, and is more effective if you want to pull specific fields from the middle.

Example:

$ echo "[email protected];[email protected]" | cut -d ";" -f 1
[email protected]
$ echo "[email protected];[email protected]" | cut -d ";" -f 2
[email protected]

You can obviously put that into a loop, and iterate the -f parameter to pull each field independently.

This gets more useful when you have a delimited log file with rows like this:

2015-04-27|12345|some action|an attribute|meta data

cut is very handy to be able to cat this file and select a particular field for further processing.

IN="[email protected];[email protected]"
IFS=';'
read -a IN_arr <<< "${IN}"
for entry in "${IN_arr[@]}"
do
    echo $entry
done

Output

[email protected]
[email protected]

System : Ubuntu 12.04.1

A different take on Darron's answer, this is how I do it:

IN="[email protected];[email protected]"
read ADDR1 ADDR2 <<<$(IFS=";"; echo $IN)

This worked for me:

string="1;2"
echo $string | cut -d';' -f1 # output is 1
echo $string | cut -d';' -f2 # output is 2

If you don't mind processing them immediately, I like to do this:

for i in $(echo $IN | tr ";" "\n")
do
  # process
done

You could use this kind of loop to initialize an array, but there's probably an easier way to do it. Hope this helps, though.

Yet another late answer... If you are java minded, here is the bashj (https://sourceforge.net/projects/bashj/) solution:

#!/usr/bin/bashj

#!java

private static String[] cuts;
private static int cnt=0;
public static void split(String words,String regexp) {cuts=words.split(regexp);}
public static String next() {return(cnt<cuts.length ? cuts[cnt++] : "null");}

#!bash

IN="[email protected];[email protected]"

: j.split($IN,";")    # java method call

while true
do
    NAME=j.next()     # java method call
    if [ $NAME != null ] ; then echo $NAME ; else exit ; fi
done

Two bourne-ish alternatives where neither require bash arrays:

Case 1: Keep it nice and simple: Use a NewLine as the Record-Separator... eg.

IN="[email protected]
[email protected]"

while read i; do
  # process "$i" ... eg.
    echo "[email:$i]"
done <<< "$IN"

Note: in this first case no sub-process is forked to assist with list manipulation.

Idea: Maybe it is worth using NL extensively internally, and only converting to a different RS when generating the final result externally.

Case 2: Using a ";" as a record separator... eg.

NL="
" IRS=";" ORS=";"

conv_IRS() {
  exec tr "$1" "$NL"
}

conv_ORS() {
  exec tr "$NL" "$1"
}

IN="[email protected];[email protected]"
IN="$(conv_IRS ";" <<< "$IN")"

while read i; do
  # process "$i" ... eg.
    echo -n "[email:$i]$ORS"
done <<< "$IN"

In both cases a sub-list can be composed within the loop is persistent after the loop has completed. This is useful when manipulating lists in memory, instead storing lists in files. {p.s. keep calm and carry on B-) }

There are some cool answers here (errator esp.), but for something analogous to split in other languages -- which is what I took the original question to mean -- I settled on this:

IN="[email protected];[email protected]"
declare -a a="(${IN/;/ })";

Now ${a[0]}, ${a[1]}, etc, are as you would expect. Use ${#a[*]} for number of terms. Or to iterate, of course:

for i in ${a[*]}; do echo $i; done

IMPORTANT NOTE:

This works in cases where there are no spaces to worry about, which solved my problem, but may not solve yours. Go with the $IFS solution(s) in that case.

In Bash, a bullet proof way, that will work even if your variable contains newlines:

IFS=';' read -d '' -ra array < <(printf '%s;\0' "$in")

Look:

$ in=$'one;two three;*;there is\na newline\nin this field'
$ IFS=';' read -d '' -ra array < <(printf '%s;\0' "$in")
$ declare -p array
declare -a array='([0]="one" [1]="two three" [2]="*" [3]="there is
a newline
in this field")'

The trick for this to work is to use the -d option of read (delimiter) with an empty delimiter, so that read is forced to read everything it's fed. And we feed read with exactly the content of the variable in, with no trailing newline thanks to printf. Note that's we're also putting the delimiter in printf to ensure that the string passed to read has a trailing delimiter. Without it, read would trim potential trailing empty fields:

$ in='one;two;three;'    # there's an empty field
$ IFS=';' read -d '' -ra array < <(printf '%s;\0' "$in")
$ declare -p array
declare -a array='([0]="one" [1]="two" [2]="three" [3]="")'

the trailing empty field is preserved.

Update for Bash=4.4

Since Bash 4.4, the builtin mapfile (aka readarray) supports the -d option to specify a delimiter. Hence another canonical way is:

mapfile -d ';' -t array < <(printf '%s;' "$in")

There is a simple and smart way like this:

echo "add:sfff" | xargs -d: -i  echo {}

But you must use gnu xargs, BSD xargs cant support -d delim. If you use apple mac like me. You can install gnu xargs :

brew install findutils

then

echo "add:sfff" | gxargs -d: -i  echo {}

In Android shell, most of the proposed methods just do not work:

$ IFS=':' read -ra ADDR <<<"$PATH"                             
/system/bin/sh: can't create temporary file /sqlite_stmt_journals/mksh.EbNoR10629: No such file or directory

What does work is:

$ for i in ${PATH//:/ }; do echo $i; done
/sbin
/vendor/bin
/system/sbin
/system/bin
/system/xbin

where // means global replacement.

I think AWK is the best and efficient command to resolve your problem. AWK is included by default in almost every Linux distribution.

echo "[email protected];[email protected]" | awk -F';' '{print $1,$2}'

will give

[email protected] [email protected]

Of course your can store each email address by redefining the awk print field.

A one-liner to split a string separated by ';' into an array is:

IN="[email protected];[email protected]"
ADDRS=( $(IFS=";" echo "$IN") )
echo ${ADDRS[0]}
echo ${ADDRS[1]}

This only sets IFS in a subshell, so you don't have to worry about saving and restoring its value.