[SOLVED] cat using readline(read -e)

gerard4143 · 05-05-2024, 10:13 PM

Is it possible to get cat, in this example, to use readline(read -e) to process/edit its input?

Code:

cat > datafile

What I'd like to see cat > datafile do is:

Code:

#! /usr/bin/env bash
# -e engages readline
while read -r -e line
do
    echo "${line}"
done

NevemTeve · 05-06-2024, 01:26 AM

Don't really understand the problem, but try this:

Code:

#! /usr/bin/env bash
# -e engages readline
while read -r -e line
do
    echo "${line}"
done >datafile

Mind you, echo is incompatible (you cannot really tell what will happen if "line" is "-n", the compatible version is printf:

Code:

printf '%s\n" "$line"

___ · 05-06-2024, 01:40 AM

No: the cat(1) program contains no such logic=functionality. You would have to use your script.

p.s. #2 (good point!) needs edit: choose either matching ' or " for printf '%s\n" format string!

pan64 · 05-06-2024, 01:58 AM

yes, would be nice to see more details, why do you want to read a line and put it into a file (in a cycle)? Use an editor to create the content and save it.

gerard4143 · 05-06-2024, 03:25 AM

Since

Code:

cat > datafile

Provides a simple way to create a text file, I thought there must/should be a simple way to engage readline(in this usage) too.

pan64 · 05-06-2024, 03:37 AM

to create a file you need not use cat, but touch. Or just simply

Code:

> datafile

Otherwise I still don't know how is it related to readline or a while loop.

___ · 05-06-2024, 03:47 AM

I just found something! (Let me/us know if it works (for what you want, since you don't want to simply use any editor program, per #4)

rlwrap cat >file

gerard4143 · 05-06-2024, 03:53 AM

Quote:

Originally Posted by ___

I just found something! (Let me/us know if it works (for what you want, since you don't want to simply use any editor program, per #4)

rlwrap cat >file

Yes! That's exactly what I was looking for.

mjolnir · 05-06-2024, 07:22 AM

Quote:

Originally Posted by ___

I just found something! (Let me/us know if it works (for what you want, since you don't want to simply use any editor program, per #4)

rlwrap cat >file

Interesting. Essentially creates a mini-text editor on the spot

gerard4143 · 05-06-2024, 02:44 PM

Quote:

Originally Posted by mjolnir

Interesting. Essentially creates a mini-text editor on the spot

A mini-text editor that has switches to modify how it behaves:

Quote:

...
-c, --complete-filenames
Complete filenames (filename completion is always case-sensitive, even with the -i option) When doing this, rlwrap keeps track command's working directory is.
-C, --command-name <command_name>|<N>
Use command_name instead of command to determine the names of history and completion files, and to initialise readline (as specified in ~/.inputrc). A numeric argument N > 0 means: use the Nth argument counting backwards from the end of the argument list
...

grail · 05-07-2024, 03:17 AM

So I am curious if you could just have done a here-doc?

Code:

cat >your_file<<EOF
type stuff
in here
EOF

gerard4143 · 05-07-2024, 03:46 AM

Quote:

Originally Posted by grail

So I am curious if you could just have done a here-doc?

Code:

cat >your_file<<EOF
type stuff
in here
EOF

I suppose you could(since the shell can support readline) but I find rlwrap a cleaner solution.