The related stub is like:
tag=('*' '#')
i=0
function output()
{
ifs="$IFS"
IFS=$'\n'
for line in $@
do
echo $'\t' "${tag[$i]}" $line
done
IFS="$ifs"
echo $i
i=$((i 1))
echo $i
i=$((i%2))
echo $i
}
output a|tee README
output b
What I want to do is:
Every time execute output
to output a message block, different prefix(${tag[$ind]}
) can be used for distinguishing itself from context. Besides, part-message can be redirect to file.
Result of it is:
* a
0
1
1
* b
0
1
1
With the pipe |tee README
, variable $i
had been reset to 0
.
Why it happened and can I implement the function by this train of thought?
Thanks.
CodePudding user response:
It happens becase, as stated at Bash manual, each command in a pipeline is executed as a separate process (i.e., in a subshell).
In order to preserve i
variable value I suggest you to enclose the two output
calls into a single shell process as follow:
#!/bin/bash
tag=('*' '#')
i=0
function output()
{
ifs="$IFS"
IFS=$'\n'
for line in $@
do
echo $'\t' "${tag[$i]}" $line
done
IFS="$ifs"
echo $i
i=$((i 1))
echo $i
i=$((i%2))
echo $i
}
(
output a
output b
) | tee README