I am parsing command output and putting results into array.
Works fine until exiting the inner loop - output array is empty.
declare -a KEYS
#-----------------------------------------------------------------------------#
get_keys()
{
# this extracts key NAMES from log in format "timestamp keycode"
$glue_dir/get_keys $ip | while read line; do
echo line: $line
set -- $line # $1 timestamp $2 keycode
echo 1: $1 2: $2
key=(`egrep "\\s$2$" "$glue_dir/keycodes"`) # tested for matching '40' against 401, 402 etc
set -- $key # $1 key name $2 keycode
KEYS+=("$1")
echo key $1
echo KEYS inside loop: "${KEYS[@]}"
done
echo KEYS outside loop: "${KEYS[@]}"
}
The output when run agains two output lines:
line: 1270899320451 38
1: 1270899320451 2: 38
key UP
KEYS inside loop: UP
line: 1270899320956 40
1: 1270899320956 2: 40
key DOWN
KEYS inside loop: UP DOWN
KEYS outside loop:
I spent an hour trying to figure this out. Please help. ;-)
Excluding the above example, the most common type of variable you'll find in Bash is arrays: The above example assigns both Linux Handbook and It's FOSS as the values for the name variable. How do you go about accessing each value though? If you run echo $name, you'll see that it prints the first value, Linux Handbook.
If the value you assign to a variable includes spaces, they must be in quotation marks when you assign them to the variable. This is because, by default, Bash uses a space as a delimiter. Bash sees the space before “Geek” as an indication that a new command is starting.
To see the active environment variables in your Bash session, use this command: env | less If you scroll through the list, you might find some that would be useful to reference in your scripts.
If the value you assign to a variable includes spaces, they must be in quotation marks when you assign them to the variable. This is because, by default, Bash uses a space as a delimiter. Here’s an example: site_name=How-To Geek. Bash sees the space before “Geek” as an indication that a new command is starting.
When you use a pipe (|
) to pass your command output to while
, your while
loop runs in a subshell. When the loop ends, your subshell terminates and your variables will not be available outside your loop.
Use process substitution instead:
while read line; do
# ...
done < <($glue_dir/get_keys $ip)
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