Prefix the contents of a file using content of another file having a single line

Question

I am trying to insert the contents of a file1.txt into file2.txt using sed. The content of file1.txt is just a single line, which is a path. I want it to be added as a prefix to each line in file2.txt as well as add another / character.

$ cat file1.txt
/psot/rot8888/orce/db/tier/data/tine

$ cat file2.txt
o1_mf_users_abchwfg_.dbf
o1_mf_toptbs2_abchrq0_.dbf
o1_mf_toptbs1_abchrl2_.dbf
o1_mf_toptbs1_abchtlf_.dbf

Desired output should be like:

/psot/rot8888/orce/db/tier/data/tine/o1_mf_users_abchwfg_.dbf
/psot/rot8888/orce/db/tier/data/tine/o1_mf_toptbs2_abchrq0_.dbf
/psot/rot8888/orce/db/tier/data/tine/o1_mf_toptbs1_abchrl2_.dbf
/psot/rot8888/orce/db/tier/data/tine/o1_mf_toptbs1_abchtlf_.dbf

Tried command:

$ sed '/o1/ r file1.txt' file2.txt >> test.txt    
$ cat test.txt
o1_mf_users_abchwfg_.dbf
/psot/rot8888/orce/db/tier/data/tine
o1_mf_toptbs2_abchrq0_.dbf
/psot/rot8888/orce/db/tier/data/tine
o1_mf_toptbs1_abchrl2_.dbf
/psot/rot8888/orce/db/tier/data/tine
o1_mf_toptbs1_abchtlf_.dbf
/psot/rot8888/orce/db/tier/data/tine

Answer 1

You can use pr for this without having to worry about sed metacharacters, delimiters, etc.

$ cat ip.txt
abcd.xyz
123.txt
foo_baz.txt
$ cat f1
/a/b/c/d/

$ pr -mts"$(< f1)" /dev/null ip.txt
/a/b/c/d/abcd.xyz
/a/b/c/d/123.txt
/a/b/c/d/foo_baz.txt

Where -m allows pasting files parallely and -s is the separator between the files to be merged. Here, /dev/null is used as a dummy for one of the files as only the separator has to be prefixed.

---

If you need to add some more characters after the contents of file containing the prefix:

$ cat ip.txt
abcd.xyz
123.txt
foo_baz.txt
$ cat f1
/a/b/c/d
$ pr -mts"$(< f1)"'/' /dev/null ip.txt
/a/b/c/d/abcd.xyz
/a/b/c/d/123.txt
/a/b/c/d/foo_baz.txt

Answer 2

This will work using any awk in any shell on every UNIX box:

$ awk 'NR==FNR{p=$0; next} {print p "/" $0}' file1 file2
/psot/rot8888/orce/db/tier/data/tine/o1_mf_users_abchwfg_.dbf
/psot/rot8888/orce/db/tier/data/tine/o1_mf_toptbs2_abchrq0_.dbf
/psot/rot8888/orce/db/tier/data/tine/o1_mf_toptbs1_abchrl2_.dbf
/psot/rot8888/orce/db/tier/data/tine/o1_mf_toptbs1_abchtlf_.dbf

Answer 3

This might work for you (GNU sed):

sed '1h;1d;G;s/\(.*\)\n\(.*\)/\2\1/' file1 file2

Copy file1 into the hold space and append it to each line in file2. Using regexp and back references, manipulate the two lines into one in the correct order.

Alternative:

sed 'x;s/.*/cat file1/e;G;s/\n//' file2

Insert file1 into the hold space, append the current line of file2, and remove the newline connecting them.

A third way:

sed 'r file1' file2 | sed -E 'N;s/(.*)\n(.*)/\2\/\1/'