How to concatenate all lines of a file from ant script?

Question

I have a text file in the following format:

cat yourfile.txt
a
b
c
d
e
f
g

I want to convert it to:

a,b,c,d,e,f,g

This is the solution I came up to now:

while read line; do printf "%s%s" $line "," ; done < yourfile.txt
a,b,c,d,e,f,g,

Two issues:

• I am getting an extra comma (,) at the end
• I know I can run this command inside a shell script and exec the shell script from my build.xml. Or there is more elegant solution?

Answer 1

You could use sed:

$ sed ':a;N;$!ba;s/\n/,/g' test.txt 
a,b,c,d,e,f,g

See this answer to read more details.

Otherwise, for the other solutions, it's very easy to remove the final comma. For example with sed :

$ cat test.txt|tr "\n" ","|sed "s/,$//g" 
a,b,c,d,e,f,g
$ while read line; do printf "%s%s" $line "," ; done < test.txt|sed "s/,$//g" # with your solution
a,b,c,d,e,f,g

Answer 2

Just use the tr command

> string=$(tr $'\n' ',' < "yourfile.txt"); echo "${string%,*}"
a,b,c,d,e,f,g

With the bash substitution to remove the trailing comma.

Answer 3

A "one"-liner taking advantage of the IFS variable and arrays:

str=$( IFS=$'\n'; arr=( $(<test.txt) ); IFS=,; echo "${arr[*]}" )

First, the entire file is read into an array, using a line-feed as the field splitter to ensure one line per element. Next, the field separator is changed to a comma so that the entire array is joined into one comma-delimited string.