将文件内容附加到 bash 文件内循环中的字符串变量不起作用

Question

I am passing a text file to a bash while running. Text file has contents I want to supply to a java program as argument. Text file has each content in a new line. The contents print fine within the loop but I need to create a concatenated string with all the contents to pass to java program and appending to a string variable in loop is not working. This is how the program looks like:

#!/bin/bash
args=""
for var in $(cat payments.txt)
do 
  echo "Line:$var"
  args+="$var "
done
echo "$args"

It prints:

Line: str1
Line:str2
 str2  // args should have appended values of each line but it got only last line

File looks like:

str1
str2

Can anyone suggests what I am doing wrong here?

Thanks

Answer 1

Your first echo is printing out the combination and not storing it in a new variable. Try:

#!/bin/bash
args=""
for var in $(cat payments.txt)
do 
  echo = "Line:$var" # this line prints but doesn't alter $var
  args+="Line:$var2 " #add Line: in here
done
echo "$args"

Answer 2

Simply use the variable in the right hand side of your assignment. Note: for var in $(cat payments.txt) is a nice example of useless use of cat .

#!/bin/bash
args=""
while IFS= read -r var; do
  args="$args $var"
done < payments.txt
echo "$args"

But instead of looping with bash, which is not very efficient, you could as well use a text processor like sed , for instance:

$ args=$(sed -n ':a;${s/\n/ /g;p;};N;ba' payments.txt)
$ echo "$args"
str1 str2