Unix & Linux Stack Exchange is a question and answer site for users of Linux, FreeBSD and other Un*x-like operating systems. It only takes a minute to sign up.
Sign up to join this community
I want to use cat with wildcards in bash in order to print multiple small files (every file is one sentence) to standard output. However, the separate file contents are not separated by a newline, which I'd like to for ease of reading.
How can I add a file delimiter of some sort to this command?
Define a shell function which outputs an end of line after every file and use it instead of cat:
endlcat() {
for file in "$@"; do
cat -- "$file"
echo
done
}
then you can use endlcat *.
The for loop loops over all provided arguments ($@) which are already escaped by the shell when you use wildcards like *. The -- is required to not choke on file names starting with a dash. Finally the echo outputs a newline.
Just use a loop instead of simple cat:
for file in /path/to/targetdir/*; do
echo "-------- $file -------"
cat "$file"
done
If you want file name between files, using tail:
tail -n +1 ./*
(In case you want tac instead of cat, some tail implementation have -r option for equivalent tac functional)
This will work:
sed '' -- *
You don't need any shell loops or otherwise, and this will always follow the output of a file with a \newline - excepting perhaps the very last.
Otherwise if you want a blank line to be output between the output of each file, this could work:
bpaste(){
eval "paste -'sd\n' -- $(x=0;for f do printf "\"\${$((x+=1))}\" - ";done)"
} </dev/null
That will always follow the output of a file with a \newline and an additional blank line.
You can call it like:
bpaste *
for n in 1 2 3; do printf "$n" >"$n"; done; sed '' -- [123]
sed must always print a \newline before it prints anything else, the last line of the last file might not get a \newline appended though. i could swear ive answered this question before.
1\n2\n3. it works. it always does. what does it print for you?
\n in RHS isn't standard. You can use sed -e '$G'.
Similar to @terdon's answer, if you happen to prefer seeing the filename in the future as well, you can use the head command:
$ head *file*
==> file_1 <==
file 1 content
==> file_2 <==
file 2 content
==> file_3 <==
file 3 content
head defaults to first 10 lines, so using it without command options for your case (one sentence per file) is perfectly fine. Otherwise, you need the -n X option.
Another way - use grep -h to simply search for the empty string in each file. This will match all lines, regardless of how many or whether newline-terminated or not. grep results are always newline-terminated. The -h option suppresses prefixing each line of output with the filename it came from:
$ printf 'a' > a
$ printf 'b\nB' > b
$ printf 'c\n' > c
$ ls
a b c
$ cat -- *
ab
Bc
$ grep -h '' *
a
b
B
c
$
Or you could use GNU paste in -serial mode with newline as the delimiter:
$ paste -s -d '\n' -- *
a
b
B
c
$
