All Questions

Tagged with
Filter by
Sorted by
Tagged with
0
votes
1answer
57 views

echo strings but extra question mark was added to the output

Strange "?" got added to the filename output. SCRIPTS="/path_to_script/" SUMMER=`cat /path_to_file/summer.txt` for i in ${SUMMER}; do cat <<- EOF > $SCRIPTS/20190430_$(echo ${i})_step4.r #...
1
vote
2answers
30 views

How to echo content into a series of new file generated by cat

I would like to write a loop to generate 22 R scripts with contents generated in echo. What went wrong in this loop that I could not get the 22 files with the corresponding content? I tested echo "i ...
-1
votes
1answer
3k views

Why does echo <<EOF … EOF not work [duplicate]

Just wondering if anyone can explain why this works: echo `cat <<EOF {"branch":"foo","value":"bar"} EOF` but this doesn't: echo <<EOF {"branch":"foo","value":"bar"} EOF (the second ...
1
vote
1answer
338 views

Piping cat into wall (e.g. cat | wall)

Why does echo foo | wall work but cat | wall not work? In the latter case, I enter a couple lines into cat, and in theory they should pipe to wall; however, nothing happens.
4
votes
1answer
251 views

Why does bash replaces text from command substitution with text thereafter

I was trying to parse some nginx config λ tree sites-enabled/ sites-available/ sites-enabled/ ├── bank.cwrcoding.com.conf ├── calendar.cwrcoding.com.conf ├── cloud.cwrcoding.com.conf ├── cwrcoding....
4
votes
4answers
2k views

echo a file as a single line with \n's

I have a multi line text file that I want to echo out as a single line file where the new lines are shown as \n. Any pointers would be great.
2
votes
2answers
4k views

Difference between 'cat < file.txt' and 'echo < file.txt' [duplicate]

I have a file named file.txt which has some content say 'abcdef', when I do cat < file.txt I get the output abcdef but when I do echo < file.txt, no output is returned. Why doesn't the input ...
1
vote
1answer
2k views

echo for Print output

I want to use the echo command to show this output: 10 item in File but seems that the below command does not work: echo "$('cat file.txt | wc -l ') items in File"
0
votes
1answer
493 views

how to send data from serial port to printer?

I have a telephone system that is connected to my old Ubuntu machine and is receiving SMDR data from it. Connected to dev/lp0 is a dot matrix printer, phone system connected to /dev/ttyS0 Currently I ...
1
vote
1answer
502 views

What happens when I echo with `-e` argument?

As you can see, I have created index.php as follows: $ echo -e "<?php passthru(\$_POST[1])?>\r<?php echo 'A PHP Test ';" > index.php and then: $ cat index.php <?php echo 'A PHP Test '...
15
votes
7answers
5k views

Why there is such a difference in execution time of echo and cat?

Answering this question caused me to ask another question: I thought the following scripts do the same thing and the second one should be much faster, because the first one uses cat that needs to open ...
33
votes
6answers
7k views

Is 'cat' a shell built-in or an external program?

When I use the type command to find out if cat is a shell built-in or an external program I get the output below: -$ type cat cat is hashed (/bin/cat) -$ Does this mean that cat is an external ...
2
votes
2answers
1k views

Why the inconsistency with using cat vs. echo piped to this sed command?

Inspired by this question: sed: N command does not read single line I wanted to understand why there appears to be an inconsistency between the following 2 commands: #1. echo This command produces ...
28
votes
1answer
21k views

Append same text to many files using cat or echo?

How can I write the same content to many text files by using cat or echo in only one command? For example I want to write "hello" to file1 and file2. I tried: echo "hello" >> file1 file2 but ...
13
votes
2answers
21k views

Unexpected results testing serial loopback using echo and cat

So I have a standard RS232 serial port that is looped back to itself by simply running a wire from Tx to Rx. I'm testing loopback by running echo and cat in two separate terminals: cat /dev/ttyS1 ...