BASH - Parse strings with special characters - bash

Question

Goal: I'm attempting to create an interactive version of docker ps. Basically, have each line be a "menu" such that a user can: start, stop, ssh, etc.
Example:
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
1. bf4a9c7de6bf app_1 "docker-php-entryp..." 7 days ago Up About an hour 443/tcp, 0.0.0.0:80->80/tcp, 9000/tcp app_1
2. 26195f0764ce app_2 "sh /var/www/html/..." 10 days ago Up About an hour 443/tcp, 127.0.0.1:8000->80/tcp app_2
Upon choosing (1/2, etc) there will be an options menu to perform various actions on the selected container.
Problem: I can't seem to figure out how to parse out each line of the docker ps command such that i'll have the Container ID and other values as array elements.
The code so far:
list=`docker ps`
IFS=$'\n' array=($list)
for index in ${!array[#]}
do
declare -a 'a=('"${array[index]}"')'
printf "%s\n" "${a[#]}"
done
The result:
CONTAINER
ID
IMAGE
COMMAND
CREATED
STATUS
PORTS
NAMES
/usr/bin/dockersh: array assign: line 9: syntax error near unexpected token `>'
/usr/bin/dockersh: array assign: line 9: `bf4a9c7de6bf app_1 "docker-php-entryp..." 7 days ago Up About an hour 443/tcp, 0.0.0.0:80->80/tcp, 9000/tcp app_1'

Answer 1

It looks like you've got a few issues with the quoting, maybe try:
list=$(docker ps)
IFS=$'\n' array=($list)
for index in "${!array[#]}"
do
declare -a a=("${array[index]}")
printf "%s\n" "${a[#]}"
done
Without proper quoting your string will be likely by re-split; consider checking your shell scripts # shell-check.net, as it usually will give you some good hints regarding bad syntax.

Answer 2

If you want to have an associative array that features a matrix with all your docker ps field accessible in row/column, you can use awk to insert separator | between fields. Then export the result in a single associative array and build the matrix according to the number of column you expect (eg 7) :
#!/bin/bash
IFS=$'|'
data=$(docker ps -a | awk '
function rtrim(s) { sub(/[ \t\r\n]+$/, "", s); return s }
{
if (NR == 1) {
head[1] = index($0,"CONTAINER ID")
head[2] = image=index($0,"IMAGE")
head[3] = command=index($0,"COMMAND")
head[4] = created=index($0,"CREATED")
head[5] = status=index($0,"STATUS")
head[6] = ports=index($0,"PORTS")
head[7] = names=index($0,"NAMES")
}
else{
for (i = 1;i < 8;i++) {
if (i!=7){
printf "%s",rtrim(substr($0, head[i], head[i+1] - 1 - head[i])) "|"
}
else{
printf "%s",rtrim(substr($0, head[i], 100)) "|"
}
}
print ""
}
}')
arr=($data)
max_column=7
row=0
column=0
declare -A matrix
for index in "${!arr[#]}"
do
matrix[$row,$column]=$(echo "${arr[index]}" | tr -d '\n')
column=$((column+1))
if [ $((column%max_column)) == 0 ]; then
row=$((row+1))
column=0
fi
done
echo "first container ID is : ${matrix[0,0]}"
echo "second container ID is : ${matrix[1,0]}"
echo "third container NAME is : ${matrix[2,6]}"
In the awk part, the aim is to insert a | character between each field for the data to be injected into an associative array with the | delimiter
As field content is aligned with field title, we store the index of each field names in head array and extract each field trimming according to the next field position
Then the matrix is build according to the max column count (7). Then each row/column can be accessed easily with ${matrix[row,column]}

Answer 3

Usual story ... don't read data with a for loop unless you know exactly the format and how to control it:
while IFS="\n" read -r line
do
array+=("$line")
done< <(docker ps)
Personally I would try and remove the numbers from the start of the lines (1., 2., etc) because then you can throw it into a select and it will give you numbers which can then be used to reference the relevant items.