zsh-users
 help / color / mirror / code / Atom feed
From: Dominik Vogt <dominik.vogt@gmx.de>
To: zsh-users@zsh.org
Subject: Re: Append newline to many files
Date: Mon, 26 Sep 2022 09:51:15 +0100	[thread overview]
Message-ID: <YzFoAzgt7bPAXCQ1@gmx.de> (raw)
In-Reply-To: <807cfc5a-78e0-d74f-160c-f68d2c463997@rayninfo.co.uk>

On Mon, Sep 26, 2022 at 09:11:04AM +0100, zzapper wrote:
>
> On 25/09/2022 14:30, Roman Perepelitsa wrote:
> > On Sun, Sep 25, 2022 at 3:21 PM Dominik Vogt <dominik.vogt@gmx.de> wrote:
> > > Assume there are thousands of text files that are not terminated
> > > with a newline.  I want to concatenate them all, but add the
> > > missing newline between files.
> > >
> > > This works but takes ten times as much time as "cat foo.*".
> > >
> > >    for i in foo.*; do cat "$i"; echo; done > out
> > >
> > > I can't really think of a fast yet simple solution.
> > This should work:
> >
> >      print >lf
> >      files=(foo.*)
> >      lf=(lf)
> >      cat -- ${files:^^lf}
> >      rm lf
> >
> This looks interesting but any chance of an explanation of how it works for
> us lesser mortals please?

It first generates a file "lf" that contains only a newline and
stores the filename in an array "lf", and the names of the files
in question in an array "files".

"${files:^^lf}" merges the two arrays in an interleaving fashion.
The result is file.1 lf file.2 lf file.3 lf ... (The shorter array
is repeated up to the other one's length).

Quite clever solution, but a bit complicated.

--

This one works too and is simple and fast:

  $ sed -e '$s/$/\n/' -e <somereplacement> foo.*
           ^^^
            |
       Replacement is done only on the last line

Ciao

Dominik ^_^  ^_^

--

Dominik Vogt


  reply	other threads:[~2022-09-26  8:53 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-09-25 13:19 Dominik Vogt
2022-09-25 13:30 ` Roman Perepelitsa
2022-09-26  8:11   ` zzapper
2022-09-26  8:51     ` Dominik Vogt [this message]
2022-09-26 19:39       ` Mikael Magnusson

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=YzFoAzgt7bPAXCQ1@gmx.de \
    --to=dominik.vogt@gmx.de \
    --cc=zsh-users@zsh.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
Code repositories for project(s) associated with this public inbox

	https://git.vuxu.org/mirror/zsh/

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).