Related
I'm trying to read a line from output, which looks like this (it comes from slurm, for those who are familiar with it):
cpu=00:00:00,energy=0,fs/disk=1389.75K,mem=556K,pages=0,vmem=203640K
After reading the line, there should be variables cpu, energy, a.s.o. with the respective value.
Initially I tried to source the output via piping:
line=$(tr ',/' ';_' <<< "cpu=00:00:00,energy=0,fs/disk=1389.75K,mem=556K,pages=0,vmem=203640K)"
source <<< $line
. <<< $line
But that doesn't work since source and . needs a file. So my working attempt now is:
file=$(mktemp)
{ sacct [...] | tr ',/' ';_' > $file && source $file && rm $file } || echo "Error"
My question would be: is there a better way to achieve the same result without creating a temporary file?
Another way that avoids the unsafe eval:
#!/usr/bin/env bash
line="cpu=00:00:00,energy=0,fs/disk=1389.75K,mem=556K,pages=0,vmem=203640K"
# Turn the / into an underscore since / can't be in an identifier
# Then read the line into an array splitting on commas
IFS=, read -ra vars <<<"${line//\//_}"
# Define all the variables
declare -- "${vars[#]}"
# And display them
declare -p cpu energy fs_disk mem pages vmem
prints out
declare -- cpu="00:00:00"
declare -- energy="0"
declare -- fs_disk="1389.75K"
declare -- mem="556K"
declare -- pages="0"
declare -- vmem="203640K"
If using bash version at laest 4.0, it is safer to parse it into an associative array that can store arbitrary key strings. Otherwise, some identifiers will fail dramatically as invalid Bash variable identifiers like fs/disk which cannot be used as a Bash variable name:
#!/usr/bin/env bash
line='cpu=00:00:00,energy=0,fs/disk=1389.75K,mem=556K,pages=0,vmem=203640K'
# Read the line into a regular array, splitting keys and values at , and = signs
IFS=,= read -r -a kv <<<"$line"
# Generates an Associative array elements delcarations
# by print quoting [key]=value pairs
# shellcheck disable=SC2155 # Safely generated declaration
declare -A map="($(
printf '[%q]=%q ' "${kv[#]}"
))"
# Print out a nice output for demo purpose:
for k in "${!map[#]}"; do
printf '%-8s %s\n' "$k" "${map[$k]}"
done
Output:
fs/disk 1389.75K
vmem 203640K
cpu 00:00:00
pages 0
energy 0
mem 556K
Alternate method to populate the Associative array from the line, using a loop:
declare -A map=()
while IFS='=' read -r -d, k v; do
map["$k"]="$v"
done <<<"$line"
try
eval `echo 'cpu=00:00:00,energy=0,fs/disk=1389.75K,mem=556K,pages=0,vmem=203640K' | tr ',/' ';_'`
I'm attempting to read an input file line by line which contains fields delimited by periods.
I want to put them into an array of arrays so I can loop through them later on. The input appears to be ok, but 'pushing' that onto the array (inData) doesn't appear to be working.
The code goes :
Input file:
GSDB.GOSALESDW_DIST_INVENTORY_FACT.MONTH_KEY
GSDB.GOSALESDW_DIST_INVENTORY_FACT.ORGANIZATION_KEY
infile=${1}
OIFS=$IFS
IFS=":"
cat ${infile} | while read line
do
line=${line//\./:}
inarray=(${line})
# echo ${inarray[#]}
# echo ${#inarray[#]}
# echo ${inarray[0]}
# echo ${inarray[1]}
# echo ${inarray[2]}
inData=("${inData[#]}" "${inarray[#]}")
done
IFS=$OIFS
echo ${#inData[#]}
for ((i = 0; i < ${#inData[#]}; i++))
do
echo $i
for ((j = 0; j < ${#inData[$i][#]}; j++))
do
echo ${inData[$i][$j]}
done
done
Field nest box in bash but it can not circumvent see the example.
#!/bin/bash
# requires bash 4 or later; on macOS, /bin/bash is version 3.x,
# so need to install bash 4 or 5 using e.g. https://brew.sh
declare -a pages
pages[0]='domain.de;de;https'
pages[1]='domain.fr;fr;http'
for page in "${pages[#]}"
do
# turn e.g. 'domain.de;de;https' into
# array ['domain.de', 'de', 'https']
IFS=";" read -r -a arr <<< "${page}"
site="${arr[0]}"
lang="${arr[1]}"
prot="${arr[2]}"
echo "site : ${site}"
echo "lang : ${lang}"
echo "prot : ${prot}"
echo
done
Bash has no support for multidimensional arrays. Try
array=(a b c d)
echo ${array[1]}
echo ${array[1][3]}
echo ${array[1]exit}
For tricks how to simulate them, see Advanced Bash Scripting Guide.
Knowing that you can split string into "array". You could creat a list of lists. Like for example a list of databases in DB servers.
dbServersList=('db001:app001,app002,app003' 'db002:app004,app005' 'dbcentral:central')
# Loop over DB servers
for someDbServer in ${dbServersList[#]}
do
# delete previous array/list (this is crucial!)
unset dbNamesList
# split sub-list if available
if [[ $someDbServer == *":"* ]]
then
# split server name from sub-list
tmpServerArray=(${someDbServer//:/ })
someDbServer=${tmpServerArray[0]}
dbNamesList=${tmpServerArray[1]}
# make array from simple string
dbNamesList=(${dbNamesList//,/ })
fi
# Info
echo -e "\n----\n$someDbServer\n--"
# Loop over databases
for someDB in ${dbNamesList[#]}
do
echo $someDB
done
done
Output of above would be:
----
db001
--
app001
app002
app003
----
db002
--
app004
app005
----
dbcentral
--
central
I struggled with this but found an uncomfortable compromise. In general, when faced with a problem whose solution involves using data structures in Bash, you should switch to another language like Python. Ignoring that advice and moving right along:
My use cases usually involve lists of lists (or arrays of arrays) and looping over them. You usually don't want to nest much deeper than that. Also, most of the arrays are strings that may or may not contain spaces, but usually don't contain special characters. This allows me to use not-to-confusing syntax to express the outer array and then use normal bash processing on the strings to get a second list or array. You will need to pay attention to your IFS delimiter, obvi.
Thus, associative arrays can give me a way to create a list of lists like:
declare -A JOB_LIST=(
[job1] = "a set of arguments"
[job2] = "another different list"
...
)
This allows you to iterate over both arrays like:
for job in "${!JOB_LIST[#]}"; do
/bin/jobrun ${job[#]}
done
Ah, except that the output of the keys list (using the magical ${!...}) means that you will not traverse your list in order. Therefore, one more necessary hack is to sort the order of the keys, if that is important to you. The sort order is up to you; I find it convenient to use alphanumerical sorting and resorting to aajob1 bbjob3 ccjob6 is perfectly acceptable.
Therefore
declare -A JOB_LIST=(
[aajob1] = "a set of arguments"
[bbjob2] = "another different list"
...
)
sorted=($(printf '%s\n' "${!JOB_LIST[#]}"| /bin/sort))
for job in "${sorted[#]}"; do
for args in "${job[#]}"; do
echo "Do something with ${arg} in ${job}"
done
done
I use Associative Arrays and use :: in the key to denote depth.
The :: can also be used to embed attributes, but that is another subject,...
declare -A __myArrayOfArray=([Array1::Var1]="Assignment" [Array2::Var1]="Assignment")
An Array under Array1
__myArrayOfArray[Array1::SubArray1::Var1]="Assignment"
The entries in any array can be retrieved (in order ...) by ...
local __sortedKeys=`echo ${!__myArrayOfArray[#]} | xargs -n1 | sort -u | xargs`
for __key in ${__sortedKeys}; do
#
# show all properties in the Subordinate Profile "Array1::SubArray1::"
if [[ ${__key} =~ ^Array1::SubArray1:: ]]; then
__property=${__key##Array1::SubArray1::}
if [[ ${__property} =~ :: ]]; then
echo "Property ${__property%%:*} is a Subordinate array"
else
echo "Property ${__property} is set to: ${__myArrayOfArray[${__key}]}"
fi
fi
done
THE list of subordinate "Profiles" can be derived by:
declare -A __subordinateProfiles=()
local __profile
local __key
for __key in "${!__myArrayOfArray[#]}"; do
if [[ $__key =~ :: ]]; then
local __property=${__key##*:}
__profile=${__key%%:*}
__subordinateProfiles[${__profile}]=1
fi
done
A bash array of arrays is possible, if you convert and store each array as a string using declare -p (see my function stringify). This will properly handle spaces and any other problem characters in your arrays. When you extract an array, use function unstringify to rebuild the array. This script demonstrates an array of arrays:
#!/bin/bash
# BASH array of arrays demo
# Convert an array to a string that can be used to reform
# the array as a new variable. This allows functions to
# return arrays as strings. Works for arrays and associative
# arrays. Spaces and odd characters are all handled by bash
# declare.
# Usage: stringify variableName
# variableName - Name of the array variable e.g. "myArray",
# NOT the array contents.
# Returns (prints) the stringified version of the array.
# Examples. Use declare to make an array:
# declare -a myArray=( "O'Neal, Dan" "Kim, Mary Ann" )
# (Or to make a local variable replace declare with local.)
# Stringify myArray:
# stringifiedArray="$(stringify myArray)"
# Reform the array with any name like reformedArray:
# eval "$(unstringify reformedArray "$stringifiedArray")"
# To stringify an argument list "$#", first create the array
# with a name: declare -a myArgs=( "$#" )
stringify() {
declare -p $1
}
# Reform an array from a stringified array. Actually this prints
# the declare command to form the new array. You need to call
# eval with the result to make the array.
# Usage: eval "$(unstringify newArrayName stringifiedArray [local])"
# Adding the optional "local" will create a local variable
# (uses local instead of declare).
# Example to make array variable named reformedArray from
# stringifiedArray:
# eval "$(unstringify reformedArray "$stringifiedArray")"
unstringify() {
local cmd="declare"
[ -n "$3" ] && cmd="$3"
# This RE pattern extracts 2 things:
# 1: the array type, should be "-a" or "-A"
# 2: stringified contents of the array
# and skips "declare" and the original variable name.
local declareRE='^declare ([^ ]+) [^=]+=(.*)$'
if [[ "$2" =~ $declareRE ]]
then
printf '%s %s %s=%s\n' "$cmd" "${BASH_REMATCH[1]}" "$1" "${BASH_REMATCH[2]}"
else
echo "*** unstringify failed, invalid stringified array:" 1>&2
printf '%s\n' "$2" 1>&2
return 1
fi
}
# array of arrays demo
declare -a array # the array holding the arrays
declare -a row1=( "this is" "row 1" )
declare -a row2=( "row 2" "has problem chars" '!##$%^*(*()-_=+[{]}"|\:;,.<.>?/' )
declare -a row3=( "$#" ) # row3 is the arguments to the script
# Fill the array with each row converted to a string.
# stringify needs the NAME OF THE VARIABLE, not the variable itself
array[0]="$(stringify row1)"
array[1]="$(stringify row2)"
array[2]="$(stringify row3)"
# Print array contents
for row in "${array[#]}"
do
echo "Expanding stringified row: $row"
# Reform the row as the array thisRow
eval "$(unstringify thisRow "$row")"
echo "Row values:"
for val in "${thisRow[#]}"
do
echo " '$val'"
done
done
You could make use of (de)referencing arrays like in this script:
#!/bin/bash
OFS=$IFS # store field separator
IFS="${2: }" # define field separator
file=$1 # input file name
unset a # reference to line array
unset i j # index
unset m n # dimension
### input
i=0
while read line
do
a=A$i
unset $a
declare -a $a='($line)'
i=$((i+1))
done < $file
# store number of lines
m=$i
### output
for ((i=0; i < $m; i++))
do
a=A$i
# get line size
# double escape '\\' for sub shell '``' and 'echo'
n=`eval echo \\${#$a[#]}`
for (( j = 0; j < $n; j++))
do
# get field value
f=`eval echo \\${$a[$j]}`
# do something
echo "line $((i+1)) field $((j+1)) = '$f'"
done
done
IFS=$OFS
Credit to https://unix.stackexchange.com/questions/199348/dynamically-create-array-in-bash-with-variables-as-array-name
I have a string in a Bash shell script that I want to split into an array of characters, not based on a delimiter but just one character per array index. How can I do this? Ideally it would not use any external programs. Let me rephrase that. My goal is portability, so things like sed that are likely to be on any POSIX compatible system are fine.
Try
echo "abcdefg" | fold -w1
Edit: Added a more elegant solution suggested in comments.
echo "abcdefg" | grep -o .
You can access each letter individually already without an array conversion:
$ foo="bar"
$ echo ${foo:0:1}
b
$ echo ${foo:1:1}
a
$ echo ${foo:2:1}
r
If that's not enough, you could use something like this:
$ bar=($(echo $foo|sed 's/\(.\)/\1 /g'))
$ echo ${bar[1]}
a
If you can't even use sed or something like that, you can use the first technique above combined with a while loop using the original string's length (${#foo}) to build the array.
Warning: the code below does not work if the string contains whitespace. I think Vaughn Cato's answer has a better chance at surviving with special chars.
thing=($(i=0; while [ $i -lt ${#foo} ] ; do echo ${foo:$i:1} ; i=$((i+1)) ; done))
As an alternative to iterating over 0 .. ${#string}-1 with a for/while loop, there are two other ways I can think of to do this with only bash: using =~ and using printf. (There's a third possibility using eval and a {..} sequence expression, but this lacks clarity.)
With the correct environment and NLS enabled in bash these will work with non-ASCII as hoped, removing potential sources of failure with older system tools such as sed, if that's a concern. These will work from bash-3.0 (released 2005).
Using =~ and regular expressions, converting a string to an array in a single expression:
string="wonkabars"
[[ "$string" =~ ${string//?/(.)} ]] # splits into array
printf "%s\n" "${BASH_REMATCH[#]:1}" # loop free: reuse fmtstr
declare -a arr=( "${BASH_REMATCH[#]:1}" ) # copy array for later
The way this works is to perform an expansion of string which substitutes each single character for (.), then match this generated regular expression with grouping to capture each individual character into BASH_REMATCH[]. Index 0 is set to the entire string, since that special array is read-only you cannot remove it, note the :1 when the array is expanded to skip over index 0, if needed.
Some quick testing for non-trivial strings (>64 chars) shows this method is substantially faster than one using bash string and array operations.
The above will work with strings containing newlines, =~ supports POSIX ERE where . matches anything except NUL by default, i.e. the regex is compiled without REG_NEWLINE. (The behaviour of POSIX text processing utilities is allowed to be different by default in this respect, and usually is.)
Second option, using printf:
string="wonkabars"
ii=0
while printf "%s%n" "${string:ii++:1}" xx; do
((xx)) && printf "\n" || break
done
This loop increments index ii to print one character at a time, and breaks out when there are no characters left. This would be even simpler if the bash printf returned the number of character printed (as in C) rather than an error status, instead the number of characters printed is captured in xx using %n. (This works at least back as far as bash-2.05b.)
With bash-3.1 and printf -v var you have slightly more flexibility, and can avoid falling off the end of the string should you be doing something other than printing the characters, e.g. to create an array:
declare -a arr
ii=0
while printf -v cc "%s%n" "${string:(ii++):1}" xx; do
((xx)) && arr+=("$cc") || break
done
If your string is stored in variable x, this produces an array y with the individual characters:
i=0
while [ $i -lt ${#x} ]; do y[$i]=${x:$i:1}; i=$((i+1));done
The most simple, complete and elegant solution:
$ read -a ARRAY <<< $(echo "abcdefg" | sed 's/./& /g')
and test
$ echo ${ARRAY[0]}
a
$ echo ${ARRAY[1]}
b
Explanation: read -a reads the stdin as an array and assigns it to the variable ARRAY treating spaces as delimiter for each array item.
The evaluation of echoing the string to sed just add needed spaces between each character.
We are using Here String (<<<) to feed the stdin of the read command.
I have found that the following works the best:
array=( `echo string | grep -o . ` )
(note the backticks)
then if you do: echo ${array[#]} ,
you get: s t r i n g
or: echo ${array[2]} ,
you get: r
Pure Bash solution with no loop:
#!/usr/bin/env bash
str='The quick brown fox jumps over a lazy dog.'
# Need extglob for the replacement pattern
shopt -s extglob
# Split string characters into array (skip first record)
# Character 037 is the octal representation of ASCII Record Separator
# so it can capture all other characters in the string, including spaces.
IFS= mapfile -s1 -t -d $'\37' array <<<"${str//?()/$'\37'}"
# Strip out captured trailing newline of here-string in last record
array[-1]="${array[-1]%?}"
# Debug print array
declare -p array
string=hello123
for i in $(seq 0 ${#string})
do array[$i]=${string:$i:1}
done
echo "zero element of array is [${array[0]}]"
echo "entire array is [${array[#]}]"
The zero element of array is [h]. The entire array is [h e l l o 1 2 3 ].
Yet another on :), the stated question simply says 'Split string into character array' and don't say much about the state of the receiving array, and don't say much about special chars like and control chars.
My assumption is that if I want to split a string into an array of chars I want the receiving array containing just that string and no left over from previous runs, yet preserve any special chars.
For instance the proposed solution family like
for (( i=0 ; i < ${#x} ; i++ )); do y[i]=${x:i:1}; done
Have left overs in the target array.
$ y=(1 2 3 4 5 6 7 8)
$ x=abc
$ for (( i=0 ; i < ${#x} ; i++ )); do y[i]=${x:i:1}; done
$ printf '%s ' "${y[#]}"
a b c 4 5 6 7 8
Beside writing the long line each time we want to split a problem, so why not hide all this into a function we can keep is a package source file, with a API like
s2a "Long string" ArrayName
I got this one that seems to do the job.
$ s2a()
> { [ "$2" ] && typeset -n __=$2 && unset $2;
> [ "$1" ] && __+=("${1:0:1}") && s2a "${1:1}"
> }
$ a=(1 2 3 4 5 6 7 8 9 0) ; printf '%s ' "${a[#]}"
1 2 3 4 5 6 7 8 9 0
$ s2a "Split It" a ; printf '%s ' "${a[#]}"
S p l i t I t
If the text can contain spaces:
eval a=( $(echo "this is a test" | sed "s/\(.\)/'\1' /g") )
$ echo hello | awk NF=NF FS=
h e l l o
Or
$ echo hello | awk '$0=RT' RS=[[:alnum:]]
h
e
l
l
o
I know this is a "bash" question, but please let me show you the perfect solution in zsh, a shell very popular these days:
string='this is a string'
string_array=(${(s::)string}) #Parameter expansion. And that's it!
print ${(t)string_array} -> type array
print $#string_array -> 16 items
This is an old post/thread but with a new feature of bash v5.2+ using the shell option patsub_replacement and the =~ operator for regex. More or less same with #mr.spuratic post/answer.
str='There can be only one, the Highlander.'
regexp="${str//?/(&)}"
[[ "$str" =~ $regexp ]] &&
printf '%s\n' "${BASH_REMATCH[#]:1}"
Or by just: (which includes the whole string at index 0)
declare -p BASH_REMATCH
If that is not desired, one can remove the value of the first index (index 0), with
unset -v 'BASH_REMATCH[0]'
instead of using printf or echo to print the value of the array BASH_REMATCH
One can check/see the value of the variable "$regexp" with either
declare -p regexp
Output
declare -- regexp="(T)(h)(e)(r)(e)( )(c)(a)(n)( )(b)(e)( )(o)(n)(l)(y)( )(o)(n)(e)(,)( )(t)(h)(e)( )(H)(i)(g)(h)(l)(a)(n)(d)(e)(r)(.)"
or
echo "$regexp"
Using it in a script, one might want to test if the shopt is enabled or not, although the manual says it is on/enabled by default.
Something like.
if ! shopt -q patsub_replacement; then
shopt -s patsub_replacement
fi
But yeah, check the bash version too! If you're not sure which version of bash is in use.
if ! ((BASH_VERSINFO[0] >= 5 && BASH_VERSINFO[1] >= 2)); then
printf 'No dice! bash version 5.2+ is required!\n' >&2
exit 1
fi
Space can be excluded from regexp variable, change it from
regexp="${str//?/(&)}"
To
regexp="${str//[! ]/(&)}"
and the output is:
declare -- regexp="(T)(h)(e)(r)(e) (c)(a)(n) (b)(e) (o)(n)(l)(y) (o)(n)(e) (t)(h)(e) (H)(i)(g)(h)(l)(a)(n)(d)(e)(r)(.)"
Maybe not as efficient as the other post/answer but it is still a solution/option.
If you want to store this in an array, you can do this:
string=foo
unset chars
declare -a chars
while read -N 1
do
chars[${#chars[#]}]="$REPLY"
done <<<"$string"x
unset chars[$((${#chars[#]} - 1))]
unset chars[$((${#chars[#]} - 1))]
echo "Array: ${chars[#]}"
Array: f o o
echo "Array length: ${#chars[#]}"
Array length: 3
The final x is necessary to handle the fact that a newline is appended after $string if it doesn't contain one.
If you want to use NUL-separated characters, you can try this:
echo -n "$string" | while read -N 1
do
printf %s "$REPLY"
printf '\0'
done
AWK is quite convenient:
a='123'; echo $a | awk 'BEGIN{FS="";OFS=" "} {print $1,$2,$3}'
where FS and OFS is delimiter for read-in and print-out
For those who landed here searching how to do this in fish:
We can use the builtin string command (since v2.3.0) for string manipulation.
↪ string split '' abc
a
b
c
The output is a list, so array operations will work.
↪ for c in (string split '' abc)
echo char is $c
end
char is a
char is b
char is c
Here's a more complex example iterating over the string with an index.
↪ set --local chars (string split '' abc)
for i in (seq (count $chars))
echo $i: $chars[$i]
end
1: a
2: b
3: c
zsh solution: To put the scalar string variable into arr, which will be an array:
arr=(${(ps::)string})
If you also need support for strings with newlines, you can do:
str2arr(){ local string="$1"; mapfile -d $'\0' Chars < <(for i in $(seq 0 $((${#string}-1))); do printf '%s\u0000' "${string:$i:1}"; done); printf '%s' "(${Chars[*]#Q})" ;}
string=$(printf '%b' "apa\nbepa")
declare -a MyString=$(str2arr "$string")
declare -p MyString
# prints declare -a MyString=([0]="a" [1]="p" [2]="a" [3]=$'\n' [4]="b" [5]="e" [6]="p" [7]="a")
As a response to Alexandro de Oliveira, I think the following is more elegant or at least more intuitive:
while read -r -n1 c ; do arr+=("$c") ; done <<<"hejsan"
declare -r some_string='abcdefghijklmnopqrstuvwxyz'
declare -a some_array
declare -i idx
for ((idx = 0; idx < ${#some_string}; ++idx)); do
some_array+=("${some_string:idx:1}")
done
for idx in "${!some_array[#]}"; do
echo "$((idx)): ${some_array[idx]}"
done
Pure bash, no loop.
Another solution, similar to/adapted from Léa Gris' solution, but using read -a instead of readarray/mapfile :
#!/usr/bin/env bash
str='azerty'
# Need extglob for the replacement pattern
shopt -s extglob
# Split string characters into array
# ${str//?()/$'\x1F'} replace each character "c" with "^_c".
# ^_ (Control-_, 0x1f) is Unit Separator (US), you can choose another
# character.
IFS=$'\x1F' read -ra array <<< "${str//?()/$'\x1F'}"
# now, array[0] contains an empty string and the rest of array (starting
# from index 1) contains the original string characters :
declare -p array
# Or, if you prefer to keep the array "clean", you can delete
# the first element and pack the array :
unset array[0]
array=("${array[#]}")
declare -p array
However, I prefer the shorter (and easier to understand for me), where we remove the initial 0x1f before assigning the array :
#!/usr/bin/env bash
str='azerty'
shopt -s extglob
tmp="${str//?()/$'\x1F'}" # same as code above
tmp=${tmp#$'\x1F'} # remove initial 0x1f
IFS=$'\x1F' read -ra array <<< "$tmp" # assign array
declare -p array # verification
The awk code below counts the frequency of the occurrence of $1. I would like the bash equivalent for this code?
a[$1]++}END{for(x in a)print a[x],x
How would I do this with a bash array?
Although there will be bash-oriented and smarter ways, the literal translation of your code will be:
declare -A a # you need to explicitly declare an associative array
while read -r x rest; do # "x" is assigned to the first field ($1) and "rest" to the rest
((a[$x]++)) # increment the count
done
for x in "${!a[#]}"; do # iterate over the array
echo "${a[$x]},$x" # print the result
done
The code above waits for the input via the stdin and you need to feed the input with a redirect or a pipe.
To count the number of occurrences of elem in arr:
printf '%s\n' "${arr[#]}" | grep -cw elem
I want to split the string and construct the array. I tried the below code:
myString="first column:second column:third column"
set -A myArray `echo $myString | awk 'BEGIN{FS=":"}{for (i=1; i<=NF; i++) print $i}'`
# Following is just to make sure that array is constructed properly
i=0
while [ $i -lt ${#myArray[#]} ]
do
echo "Element $i:${myArray[$i]}"
(( i=i+1 ))
done
exit 0
It produces the following result:
Element 0:first
Element 1:column
Element 2:second
Element 3:column
Element 4:third
Element 5:column
This is not what I want it to be. When I construct the array, I want that array to contain only three elements.
Element 0:first column
Element 1:second column
Element 2:third column
Can you please advise?
Here is how I would approach this problem: use the IFS variable to tell the shell (bash) that you want to split the string into colon-separated tokens.
$ cat split.sh
#!/bin/sh
# Script to split fields into tokens
# Here is the string where tokens separated by colons
s="first column:second column:third column"
IFS=":" # Set the field separator
set $s # Breaks the string into $1, $2, ...
i=0
for item # A for loop by default loop through $1, $2, ...
do
echo "Element $i: $item"
((i++))
done
Run it:
$ ./split.sh
Element 0: first column
Element 1: second column
Element 2: third column
if you definitely want to use arrays in Bash, you can try this way
$ myString="first column:second column:third column"
$ myString="${myString//:/ }" #remove all the colons
$ echo "${myString}"
first column second column third column
$ read -a myArr <<<$myString
$ echo ${myArr[#]}
first column second column third column
$ echo ${myArr[1]}
column
$ echo ${myArr[2]}
second
otherwise, the "better" method is to use awk entirely
Note that saving and restoring IFS as I often seen in these solutions has the side effect that if IFS wasn't set, it ends up changed to being an empty string which causes weird problems with subsequent splitting.
Here's the solution I came up with based on Anton Olsen's extended to handle >2 values separated by a colon. It handles values in the list that have spaces correctly, not splitting on the space.
colon_list=${1} # colon-separate list to split
while true ; do
part=${colon_list%%:*} # Delete longest substring match from back
colon_list=${colon_list#*:} # Delete shortest substring match from front
parts[i++]=$part
# We are done when there is no more colon
if test "$colon_list" = "$part" ; then
break
fi
done
# Show we've split the list
for part in "${parts[#]}"; do
echo $part
done
Ksh or Bash
#! /bin/sh
myString="first column:second column:third column"
IFS=: A=( $myString )
echo ${A[0]}
echo ${A[1]}
Looks like you've already found the solution, but note that you can do away with awk entirely:
myString="first column:second column:third column"
OIFS="$IFS"
IFS=':'
myArray=($myString)
IFS=$OIFS
i=0
while [ $i -lt ${#myArray[#]} ]
do
echo "Element $i:${myArray[$i]}"
(( i=i+1 ))
done