Unix - how to merge filename inside content with cat and baseline? - unix

Question

I want to a merge files (one line) with filename at the begining of the line.
'cat' does a merge on files and 'basename -a' gives filemanes but I don't know how to get both ?
$ echo "content1" > f1.txt
$ echo "content2" > f2.txt
$ cat f*.txt > all.txt
$ cat all.txt
content1
content2
$ basename -a f*.txt
f1.txt
f2.txt
Would like this result :
$ cat all.txt
f1.txt content1
f2.txt content2

Answer 1

Just use grep -H. Post process to change the delimiter:
$ for i in 1 2; do echo content$i > f$i.txt; done
$ grep -H . *.txt
f1.txt:content1
f2.txt:content2
$ grep -H . *.txt | sed 's/:/ /'
f1.txt content1
f2.txt content2
or,
$ awk '{printf "%s\t%s\n", FILENAME, $0}' *.txt
f1.txt content1
f2.txt content2

Answer 2

Use a loop. Iterate over every *.txt file, echo its name to the output file without a newline (done with echo -n,) append its contents to the output file, and finally append a newline. Note that >> appends. Using > would overwrite.
rm -f all.txt
for f in *.txt; do echo -n "$f " >> all.txt; cat "$f" >> all.txt; echo >> all.txt; done
If your input files already contain a newline at the end, then you skip the final echo and just do:
for f in *.txt; do echo -n "$f " >> all.txt; cat "$f" >> all.txt; done
If you're using tcsh instead of bash, then you can use foreach, but you can't write the whole loop in a single command. Normally you would write this in a script:
foreach f (*.txt)
echo -n "$f " >> all.txt
cat "$f" >> all.txt
end
To get this in a single command line you need something like this instead:
printf 'foreach f (*.txt)\n echo -n "$f " >> all.txt\n cat "$f" >> all.txt\n end' | tcsh