Shell Programming and Scripting

I would like to append a string at the end of each row of a .dat file.
please give me some advice? Thanks.

e.g.
#content in abc.dat
aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
...


#after running the script/command, "bbbbbbbbbb" will be appended as follow.
aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbb
aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbb
aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbb
...

It is just me or does this look like an exam question?

I have writen a simple script to arhieve my purpose. However, "There is not enough memory available now" is prompted. Can my script be optimized to reduce resource? Thanks.

append_string=`cat ${source_file} | awk ' BEGIN { FS = "\n" } { if ($1 ~ "SWIFT5" ) {print $1, " :: SEND = N :: SEV = 0 :: ERROR = 11414 :: COMP = Name :: "
} else {print $1;} }'`

Here is a sed solution.

Code:

str="string to be attached"
sed -e "s/.*/&$str/g" input.txt

A Python alternative

Code:

#!/usr/bin/python
string_to_attach = "a string to attach"
for line in open("yourfile"):
    line = line.strip()
    print "%s%s" %( line, string_to_attach )

prompt:

Code:

# python test.py > outfile

For the sed solution,


The Pattern is constructed with a variable string inside a text.
e.g.
aaa123aaa
aaa4 5aaa
aaa678aaa

sed -e "s/aaa*aaa/&$str/g" ${source_file}

Why I can't use "*" to find the pattern?

I didnt quite get what you are looking for.

str should contain the string you want to append.

Does this help ?

Code:

sed -e "s/aaa.*aaa/&$str/g" ${source_file}