About bash : How-to-pipe-input-to-a-Bash-while-loop-and-preserve-variables-after-loop-ends
Question Detail
Bash allows to use: cat <(echo "$FILECONTENT") Bash also allow to use: while read i; do echo $i; done Question Answer
The correct notation for Process Substitution is:
while read i; do echo $i; done < <(echo "$FILECONTENT")
The last value of i assigned in the loop is then available when the loop terminates.
An alternative is:
echo $FILECONTENT |
{
while read i; do echo $i; done
...do other things using $i here...
}
The braces are an I/O grouping operation and do not themselves create a subshell. In this context, they are part of a pipeline and are therefore run as a subshell, but it is because of the |, not the { ... }. You mention this in the question. AFAIK, you can do a return from within these inside a function.
Bash also provides the shopt builtin and one of its many options is:
lastpipe
If set, and job control is not active, the shell runs the last command of a pipeline not executed in the background in the current shell environment.
Thus, using something like this in a script makes the modfied sum available after the loop:
FILECONTENT="12 Name
13 Number
14 Information"
shopt -s lastpipe # Comment this out to see the alternative behaviour
sum=0
echo "$FILECONTENT" |
while read number name; do ((sum+=$number)); done
echo $sum
Doing this at the command line usually runs foul of 'job control is not active' (that is, at the command line, job control is active). Testing this without using a script failed.
Also, as noted by Gareth Rees in his answer, you can sometimes use a here string:
while read i; do echo $i; done <<< "$FILECONTENT"
This doesn't require shopt; you may be able to save a process using it.
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Jonathan Leffler explains how to do what you want using process substitution, but another possibility is to use a here string:
while read i; do echo "$i"; done <<<"$FILECONTENT"
This saves a process.
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This function makes duplicates $NUM times of jpg files (bash)
function makeDups() {
NUM=$1
echo "Making $1 duplicates for $(ls -1 *.jpg|wc -l) files"
ls -1 *.jpg|sort|while read f
do
COUNT=0
while [ "$COUNT" -le "$NUM" ]
do
cp $f ${f//sm/${COUNT}sm}
((COUNT++))
done
done
}