Pasting some text with tabs into a here-document in a PuTTY window

Question

I have a string with tab delimited data that looks like:

h1  h2
a1  b1
a2  b2

I produced it with Notepad on Windows. I created tab delimited data, ensuring that tabs and not spaces are used.

I connect to a Linux server via SSH using PuTTY. I would like to write the file to /tmp/test.txt and preserve the tabs. So I run cat <<EOF >/tmp/test.txt. I copy the text from Notepad and paste it into the putty session. Then I enter EOF.

However, that produces a file without tabs having the contents of:

h1h2
a1b1
a2b2

I've found that this works:

sed 's/\\t/\t/g' > /tmp/test.txt << EOF
h1\th2
a1\tb1
a2\tb2
EOF

However, it required that I change my input string to use '\t' instead of actual tabs. What is a more elegant/simple solution that allows me to take a string literal as-is from Windows and write it into a file on the remote Linux machine?

I am SSHed into a Linux server from Windows via putty. The server is:

• Distribution: Red Hat Enterprise Linux Server release 6.6 (Santiago)
• Bash version: 4.1.2(1)-release (x86_64-redhat-linux-gnu)
• cat: coreutils-8.4-37.0.1.el6.x86_64

Answer 1

When you type into a shell, the shell recognizes some characters as commands. For example, the carriage return character (the character sent by the Enter key) causes the shell to execute the command. The tab character causes the shell to perform completion. When you paste something into the PuTTY terminal window, from the shell's point of view, that's the same thing as if you'd typed these characters. So at the point the tab character is pasted, the shell performs completion, it doesn't insert a tab.

The easiest way to copy a file without it being transformed would be to use PuTTY's companion program PSCP or PSFTP to copy the file. This is the simplest way conceptually, but it does have the overhead of running another program, authenticating, choosing a directory, etc.

If you want something inline, you can paste directly into cat, rather than in a here document. Then you'd be pasting into the terminal's line editor, not into the shell's line editor. As the terminal's line editor is very primitive, only a few control characters have a special meaning there, not including tab. Press Ctrl+D at the beginning of a line to terminate the input.

[darkstar /]$ cat >text.txt
Paste
Ctrl+D
[darkstar /]$ 

I you want to transfer arbitrary data over a medium that interprets control characters, you can encode it into a form that uses only “tame” characters. Base64 is one; it doesn't use any control character and ignores whitespace and newlines. GNU coreutils, which is part of the basic installation on Linux and Cygwin, includes a base64 command. On the sender side, run base64 <file-to-decode, e.g.

• On Windows: run base64 c:/path/to/test.txt from a Cygwin terminal
• Copy the output.
• In the shell in the PuTTY window, type `base64 -d >/tmp/test.txt and press Enter.
• Paste the output from base64.
• Press Ctrl+D.

Answer 2

I'm not entirely sure what problem you're having - on my RHEL install, cat works if I give it tab stops. However as a more general solution perhaps:

 #!/usr/bin/perl

 use strict;
 use warnings; 

 while ( <> ) { 
     s/\s+/\t/g; 
     print;  
 }

Will take 'input' on either STDIN (catted into) or as filenames (e.g. myscript.pl <filename>) and convert all whitespace to tab stops.

Answer 3

If you would like a more simple solution than perl script, you can use sed, anyway that perl script is simple too.

echo "hello    world" | sed 's/\(\t\+\)/\t/g'

Anyway, using redhat 5 I don't see any problem using cat command

rpm -qf $(which cat)
coreutils-5.97-34.el5

Answer 4

The bash manual explains (on [n]<<[-]word):

If any part of word is quoted, the delimiter is the result of quote removal on word, and the lines in the here-document are not expanded. If word is unquoted, all lines of the here-document are subjected to parameter expansion, command substitution, and arithmetic expansion, ...

while cat >/tmp/test.txt <<'EOF' might do, it does not: TABs are still expanded. As it seems to be the readline library, there is a somewhat easy solution:

user@host:~> bash --noediting
user@host:~> cat >/tmp/test.txt <<EOF

(paste your data now)

EOF
user@jhost:~> exit

(leave the extra shell)

Another tool to exchange files between Windows and SSH-enabled UNIX is WinSCP.