Linux: How would I pipe text into a program properly?

Question

I've looked but can't find anything. A program for example, a TTS I use lets you do the following:

~#festival -tts | echo "I am to be spoken"

Which is really nice, but for programs I use such as hexdump, I don't know how to pipe text into it. I can REALLY use some of these things, some examples I tried (but failed) are like so:

~#gtextpad < dmesg
      //(how do I put the contents into the text pad for display? not just into a file)
~#hexdump | echo "I am to be put into hexdump"
      //(How do I get hexdump to read the echo? It normally reads a file such as foo.txt..)

score 9 · Accepted Answer · answered Feb 07 '10 at 05:29

9

here are some ways to pass text to hexdump

Stdin:

echo "text" | hexdump

Here document

hexdump <<EOF
text
EOF

to process entire file

hexdump file

answered Feb 07 '10 at 05:29

ghostdog74

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Ah. The other way around, Now I can do some useful automated things I've wanted. – oni-kun Feb 07 '10 at 05:36

score 4 · Answer 2 · answered Jul 13 '13 at 22:30

4

On bash, you can also do

hexdump <<< "Pipe this text into hexdump"

answered Jul 13 '13 at 22:30

rmmh

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See this question for an explanation of `<<<`: https://unix.stackexchange.com/questions/80362/what-does-mean – Andrew Keeton Jan 02 '20 at 15:54

score 3 · Answer 3 · answered Feb 07 '10 at 05:20

The data flow in a pipeline (series of commands separated by pipe symbols) flows from left to right. Thus, the output from command1 below goes to the input of command2, and so on.

command1 |
command2 |
command3 arg1 arg2 arg3 |
sort |
more

So, to get the output of 'echo' into 'hexdump', use:

echo "I am to be dumped" | hexdump

I don't see how the 'festival' command you show can work. The shell does enough plumbing that without making unwarranted assumptions and doing a lot of skulduggery and then still relying on scheduling decisions in the kernel to get things 'right', I don't see how it can be made to work.

score 2 · Answer 4 · answered Feb 07 '10 at 05:17

2

From the hexdump(1) man page:

The hexdump utility is a filter which displays the specified files, or the standard input, if no files are specified, in a user specified format.

So:

echo "I am to be put into hexdump" | hexdump

answered Feb 07 '10 at 05:17

Ignacio Vazquez-Abrams

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Linux: How would I pipe text into a program properly?

4 Answers4