Questions tagged [echo]
Questions about either the shell builtin or `/bin/echo`. This tag should not be used if your question is simply about printing to the terminal, only apply it if your question is specific to the `echo` command.
504
questions
0
votes
1
answer
51
views
How to read files of kind "-diary.txt-" using echo?
I have a file named "-diary.txt-", I need to get it's content. When trying to read it using echo < "-diary.txt-", it returns a blank string. I did some research, and came up ...
- 13
0
votes
1
answer
79
views
Why does this "-e" option for echo get written to a file (although not enclosed in double quotes)? [duplicate]
#!/usr/bin/env python3
from subprocess import run
from sys import modules
def main():
doas()
def doas():
ch = input("Ready to proceed with setting up doas?[Y/n]?")
if ch == 'y':
...
- 561
0
votes
1
answer
40
views
Flush output continuously with xargs
The function output the size of the downloaded file and the speed of transfer separated with newline.
Example:
20 #<< data
3.0M #<< speed
25
1.2M
Now, it goes like this:
output_data_func |...
- 162
0
votes
0
answers
31
views
printf and echo -n Work Differently - Why? [duplicate]
echo -n
my_function() {
echo -n "$@"
}
my_function hello world
I get my desired output:
hello world
printf
my_function() {
printf "$@"
}
my_function hello world
I get only ...
- 540
1
vote
1
answer
30
views
Concatenating string passed into a control sequence
I have this echo invocation that prints a blue bar in a Bash terminal:
echo $'\e[48;2;0;0;255m \e[0m'
I would like to pass some variables to it, something like (this doesn't work):
...
- 11
0
votes
1
answer
85
views
Does the echo command create a swap file when it writes a line to a file?
I am currently working on a personal project, and I would like to simply record logs in the following way using the echo command.
My question is if the echo command accesses the same file at the same ...
- 11
0
votes
2
answers
121
views
Why is echo "\*" the same as echo "\\*"
Title.
echo "\*" has the exact same output as echo "\\*", \*. I am using GNU bash 5.2.15.
I expected echo "\\*" to output \*, but I do not know why echo "\*" ...
- 103
0
votes
1
answer
26
views
extract last part of filename using echo - having assigned variables using wildcards
I am trying to extract parts of a filename, where I want to extract everything after the first _
and I have found a working solution, see below
file=22NGS71294_S191_R1_001.fastq.gz
echo $file
...
- 3
1
vote
1
answer
28
views
watch -n1 $() does not run $() every interval
watch -n1 $() does not update $().
what is the workaround?
here is my example:
watch -n1 echo $(( $(date +%s -d "sun") - $( date +%s ) ))
this results in
Every 1.0s: echo 106602 ...
0
votes
1
answer
84
views
Why I can pipe echo into bc, but I can't do the same with printf?
I can pipe echo into bc.
But I cannot do the same with "printf": it gives syntax error.
❯ echo "100-5" | bc
95
❯ printf "%s" "100-5" | bc
(standard_in) 1: ...
- 273
0
votes
3
answers
124
views
What does echo $$ do? [duplicate]
I was messing around with echo and was trying stuff like echo ~. When I was trying to use $ to substitute environment variables I accidentally tried echo $$. Surprisingly instead of an empty line I ...
0
votes
1
answer
31
views
Some dump comes out when giving inputs to program by using a pipe in Linux
I'm now trying to do exploitation by using a race condition bug.
However, a problem occurs; Values that I have never given to the process come out.
Below is a description of the case.
Scenario:
An ...
- 1
0
votes
0
answers
56
views
echo incorrectly interpreting colors
I want my terminal prompt to change color depending on success of the previous command. Currently I achieve this with the following script:
exitstatus()
{
if [[ $? == 0 ]]; then
echo -e &...
10
votes
3
answers
1k
views
Temporarily unset bash option -x
I like to use set -x in scripts to show what's going on, especially if the script is going to run in a CI/CD pipeline and I might need to debug some failure post-hoc.
One annoyance with doing this is ...
- 206
0
votes
1
answer
97
views
What are the types of echo output (Opaque, Semi-Opaque, Clear text) [closed]
I have an assignment from my lecturer to Write a script that will show each of the 3 types of echo (opaque, semi-opaque, and cleartext)
The issue is, I don't know what the types are. I have searched ...
0
votes
2
answers
28
views
Echo message when flag is detected
This works well at running Seamonkey only once per 24 hours.
I would like to show a message if the flag is detected.
I am not sure where to put that echo statement.
#!/bin/bash
#
# Run this script ...
- 133
0
votes
1
answer
25
views
Echo'ing the variable muliple times while reading the variable values from a file
I am trying to write a bash script which would read values from a file and echo out the values. But for what ever reason it is not working correctly.
My first file is having the below values
Alts Risk ...
- 101
3
votes
2
answers
1k
views
How can I write in multiple files at once using 'cat'?
This question is kind of related to my previous question.
This is the output of tree:
[xyz@localhost Semester1]$ tree
.
├── Eng
│ ├── credits
│ ├── links
│ └── notes
├── IT
│ ├── credits
│ ├─...
- 301
0
votes
4
answers
268
views
Read from file; and execute its content line by line; terminate at first error [closed]
I am reading the content of a file do.sh using the bash command line structure. I want to execute each line of this file, line by line, so that, later, I can add some text to the script which can ...
4
votes
2
answers
424
views
How to print a double quote in POSIX scripting?
So far, I've been using "\"" to print a double quote:
$ x="abc def"
$ echo "x=\"$x\""
x="abc def"
However, it seems like that behavior is ...
- 2,980
1
vote
0
answers
131
views
How to export a variable and log the details to the console at the same time?
How to export a variable and log the details at the same time? For example, how to do the following in a one liner?
export myvar=$var1$var2$var3
echo $myvar
- 119
2
votes
2
answers
1k
views
Fastest way to write bash variable to a file
I want to generate some big files for some experiment.
This is my script. It creates a file then reads it to a variable and then tries to write it as many times defined in the loop in files:
#! /usr/...
- 846
0
votes
1
answer
529
views
can 'cat' command be a pipe target?
I used to do bash programming long, long time ago but over a period of time I moved onto other programming languages. My work demands I look into a bash script and I found this piece of code which I ...
- 103
1
vote
2
answers
278
views
zsh: alias or shell function to only echo its command line, including shell control characters
Using zsh, I'd like to create an alias or a shell function that operates as follows:
I want this alias or shell function to echo its command line without honoring any shell control characters such as &...
- 535
3
votes
2
answers
563
views
file listing: difference between ls and echo *
on a lustre file system with thousands of file in directories, each time I type ls I get a large delay until files are listed. Same happens with other commands that need file listing. But if I type ...
- 149
0
votes
1
answer
83
views
echo >>regular_file vs echo >>&fd: one closes, other does not
In my observation, echo to regular file echo >>regular_file opens the file, appends to it, and then closes the file. Whereas echo to an open file descriptor echo >>&fd* doesn't close ...
- 566
1
vote
1
answer
317
views
Why is it recommended to use "printf -- <arguments>" instead of "echo <arguments>?" [duplicate]
In the Bash Pitfalls on "Greg's Wiki" I found the following quote:
In fact, the echo command cannot be used with absolute safety here. If
the variable contains -n for example, echo will ...
- 121
0
votes
1
answer
40
views
I am trying to understand what a particular echo statement does
I am trying to understand what the second echo statement does exactly (it's an existing script)..
echo "Triggering report.. "
curl -s -X POST "http://aaa.bbb"
echo -e \ '\
'
I ...
- 103
2
votes
1
answer
510
views
How to display echo messages from a systemd-timer script in journalctl?
I run via a systemd timer a shell script that starts some programs (they display some output) and uses echo to provide some feedback.
root@srv ~ [127]# cat /etc/systemd/system/borg.timer
[Unit]
...
- 1,455
2
votes
3
answers
852
views
How to add echo write commands to sudoers
I would like to add a command that use echo to write to files into sudoers so that it can be run without a password.
Typically the command would go like this:
sudo sh -c 'echo 1 > /sys/devices/...
- 2,011
7
votes
2
answers
1k
views
How to write binary values into a file in Bash instead of ASCII values
I am dealing with an embedded system which has some memory that is accessible by a file descriptor (I have no idea what am I saying, so please correct me if I am wrong).
This memory is 32 kB and I ...
- 846
3
votes
3
answers
1k
views
How to print to stdout after exec >/dev/null
In a script, I have a long list of commands that print to stdout. I want to hide all output. So instead of redirecting each command, I put
exec >/dev/null
at the beginning.
What options do I have ...
- 2,980
0
votes
0
answers
28
views
Why is my script misbehaving sometimes? [duplicate]
I have created a script that can split an audio file into smaller files via ffmpeg using timestamps, and another script which can take in timestamps & names in batches. My use for this script ...
- 2,011
2
votes
3
answers
2k
views
Stuck at removing a trailing newline from a string variable
Sometimes simplest things take your time in shell scripting like crazy.
Content='me \n you \n him \n'
echo $Content > Names.txt
When I open the Names.txt it has two empty lines at the end.
I want ...
- 545
-1
votes
1
answer
650
views
Why is “echo $SHELL” not captured by remote SSH output?
When I capture the output of a remote SSH call using cat, whether in bash or in Python, things work as expected.
E.g, this works just fine:
import subprocess
rc = subprocess.getoutput(“ssh user@host; ...
- 139
0
votes
2
answers
444
views
How to correctly line break and concatenate a string in a bash script
I have a Bash script with a function to log messages with time and status, and I want to keep my script 80 column only:
#!/bin/bash
log_message() {
echo "[$(date)]-[$1] : $2" >> log....
- 846
0
votes
0
answers
236
views
write terminal output to file while keeping new lines [duplicate]
when I call env to see the environment variables it shows nicely with new lines:
$ env
SHELL=/bin/sh
EDITOR=vi
PWD=/home/user
...
but when I want to store this to a file the new lines get ...
- 846
0
votes
0
answers
462
views
Why is shell/terminal printing extra new line. What can be done to prevent it?
root@kali-linux:~# echo -ne "hi"
hi
root@kali-linux:~# echo "hi"
hi
root@kali-linux:~#
I am using bash shell, xfce + i3wm + stterm in kali. On previous version of kali, there ...
- 123
0
votes
2
answers
2k
views
Trying to create a while loop to output content of one file to another
I am trying to create a while loop so that it takes content from one file and creates some content on another file. But what i noticed is that it is only creating the last line of the file instead of ...
- 101
0
votes
0
answers
46
views
Weird behaviour of string concatenation in Bash [duplicate]
I have a problem with bash and string concatenation.
Let's say that I have 2 variables:
FILENAME=/rust-analyzer-x86_64-unknown-linux-gnu.gz
URL=$(http --headers https://github.com/rust-lang/rust-...
- 111
17
votes
1
answer
6k
views
Why is echo -e behaving weird in a Makefile?
I was writing a Makefile (on Ubuntu 20.04, if it's relevant) and noticed some interesting behavior with echo. Take this simple Makefile:
test.txt:
@echo -e 'hello\nworld'
@echo -e '...
- 805
0
votes
0
answers
126
views
Inquirer program answer questions by piping
Hi I have written this program with inquirer.js it has a list question and after that a text input.
I want to answer both questions with piping.
If I just keep the list question, I can easily use yes ...
- 101
0
votes
0
answers
649
views
writing a private key from a variable to file [duplicate]
I have a scenario where I am exporting private key and writing it to a file.
export CLI_KEY_FILE="-----BEGIN PRIVATE KEY-----
3MFPAZh1qa8XsLdlBBwRypZ8QxTzjdYe4trERoWoLMuaZWsAVRzTypCZG0/Hhfin
...
- 85
-2
votes
2
answers
405
views
Why does echo in Bash modify the content of a independent variable?
I have the following code (minimal example).
#!/bin/bash
...
- 222
-2
votes
1
answer
225
views
How to handle "&" in Echo command [duplicate]
I required to Echo following information but I am getting error.
echo Mumbai & Banglore
But I am getting error as follows,
'Banglore' is not recognized as an internal or external command,
...
- 1
2
votes
1
answer
1k
views
bash associative array where values are variables, print each value's variable name
I have the following associative array.
var1="dog"
var2="cat"
var3="moose"
declare -A asar01=(
["one"]="$var1"
["two"]="$var2"
[&...
- 542
0
votes
1
answer
233
views
Source a script in Linux for all users logging in that echo some things
We have CENTOS 7.x Linux with bash shell. I need a some environment variables to be set and some messages involving these env vars to be echoed (a banner kind of thing, but dynamic because it's got ...
- 1
0
votes
0
answers
1k
views
Bash: echo command into tty
I've a service written in Python that can receive commands and does things, here is how it is built:
print("\nWelcome!\n")
for line in sys.stdin:
cmd=line.rstrip()
...
- 721
10
votes
4
answers
3k
views
How do I print the nth argument of a script, when n isn't known until runtime?
I am writing a shell script and I need to print the nth argument of the script.
For example,
suppose we have n=3 and our script is run with enough arguments.
Now I need to print the nth argument, i.e. ...
- 199
0
votes
1
answer
2k
views
help using bind/unbind to power on/off USB drive
I'm trying to power on/off an USB drive using bind/unbind command following this post, can someone please point me to the right direction where to find tutorial/explanation on bind/unbind usb drive (...
- 71