Questions tagged [stderr]
Standard error is another output stream typically used by programs to output error messages or diagnostics.
-1
votes
1answer
46 views
What controls the buffering of stdout stderr?
What part of the system sets up the buffering of the three standard streams when a program is started?
Is this part of linux, or glibc, or maybe bash? Does POSIX define the behaviour, or is it part ...
1
vote
0answers
44 views
Color rm -i prompt messages
I'm looking for a way to apply custom colors to messages emitted by the rm -i command:
~ $ rm -i file.txt
rm: remove regular empty file 'file.txt'?
I understand that I need to redirect the stderr as ...
0
votes
1answer
31 views
How can I store output in bash variable and suppress output to stderr and stdout? [duplicate]
If i'm doing
oidvalue=$(snmpget -v 2c -c public localhost 1234)
This will store the output of that command in oidvalue, however as it is now, it will print some error to the screen. How can I ...
3
votes
2answers
292 views
Why can't I get pgrep output right to variable on bash script?
I'm trying to make a script to either quit compton if it's running or start it if it's not running. I've read from man that it should exit 1 if process is found, so I've tried to make a script that ...
0
votes
2answers
45 views
Append string on redirect
When redirecting all output to stderr:
stat file >&2
... if the command throws an error (e.g. file does not exist) how can one prepend some arbitrary text, such as:
<<MY ARBITRARY TEXT&...
1
vote
2answers
39 views
Redirect specific error in stderr
So I want to use an if statement to run a script to import some functions.
$ cat functions.sh
#!/bin/bash
sampleFunction(){
if [[ ! "${fakeVariable}" == '2' ]]
then
read -n1 -r -p "...
0
votes
1answer
43 views
Confusion about stdout and stderr on the start-up terminal
I have an embedded Linux system with different programs running from start-up. Some of these programs write to stdout and stderr with printf().
When I first log into the system via SSH, I can see all ...
0
votes
2answers
137 views
Nohup: Redirect stderr to file and dismiss stdout
Per default, nohup writes stdout to nohup.out and dismisses stderr. I would like to have it the other way around:
write stderr to a file and dismiss stdout.
0
votes
0answers
30 views
How do I know that the output is stderr? [duplicate]
When writing a very simple command in my terminal, like
find ./ -name "pattern"
I get a lot of 'errors' because I am not searching as sudo, and as consequence I get a lot of 'Permission denied' ...
-1
votes
1answer
36 views
Gzip verbosity goes to standard error
When I want to redirect any verbose output I usually do the following,
[arif@arif test]$ rsync -v /home/arif/storage . 1> stdout
[arif@arif test]$ cat stdout
storage
sent 177 bytes received 35 ...
0
votes
2answers
62 views
STDOUT + STDERR output … is there any difference between considering the output to be an empty string vs NULL
I'm writing some application code that is used to execute Linux shell commands, and it then logs the command details into an SQL database. This includes the output of STDOUT + STDERR (separately).
...
2
votes
2answers
75 views
Bash: turn stderr back on after suppressing
I've made this script which automates installing/uninstalling git. In my function for testing if git is installed, I use the git --version command and test the return code.
I dislike the stderr ...
-5
votes
1answer
252 views
Is data streamed as stdout/stderr removed after it appears in the terminal? [closed]
I know that stdout/stderr are a streams of data (uncommonly called "sources of data"), and that these streams of data also typically appear as terminal output.
After the stdout/stderr data appears in ...
6
votes
3answers
342 views
How can I use sed to edit bash debug output? (bash -x)
#!/bin/bash -x
echo This is a script that has debugging turned on
This script outputs
+ echo This is a script that has debugging turned on
This is a script that has debugging turned on
I want to ...
13
votes
2answers
921 views
What prevents stdout/stderr from interleaving?
Say I run some processes:
#!/usr/bin/env bash
foo &
bar &
baz &
wait;
I run the above script like so:
foobarbaz | cat
as far as I can tell, when any of the processes write to stdout/...
3
votes
3answers
205 views
How to `paste` stdin next to stderr?
Usually paste prints two named (or equivalent) files in adjacent columns like this:
paste <(printf '%s\n' a b) <(seq 2)
Output:
a 1
b 2
But when the two files are /dev/stdin and /dev/...
1
vote
4answers
890 views
How to redirect stderr in a variable but keep stdout in the console [duplicate]
My goal is to call a command, get stderr in a variable, but keep stdout (and only stdout) on the screen. Yep, that's the opposite of what most people do :)
For the moment, the best I have is :
#!/...
2
votes
1answer
386 views
What is non-standard input/output/error
I have read books/tutorials which mention standard input/output/error. My understanding is that:
standard input/output/error are concepts of a process (i.e. if someone mentions standard input/output/...
0
votes
2answers
77 views
Remove lines from stderr [duplicate]
There is custom message that comes each time I ssh or scp which I would like to hide. I still want the rest of the stderr to go to stderr output.
For example: a.sh contain one line: ssh example.com "...
4
votes
2answers
443 views
How to suppress stdout / stderr from a shell script output?
I have a script that is suppose to stop and recover the process to run in the background:
process_id=`ps -eaf | grep -i daemon | grep -v grep | grep -v status | grep -v stop | awk '{print $2}'`
(kill ...
4
votes
1answer
95 views
How to see from which file descriptor output is coming?
How to see from which file descriptor output is coming?
$ echo hello
hello
$ echo hello 1>&2
hello
all are going to /dev/pts/0
but there are 3 file descriptors 0,1,2
2
votes
2answers
60 views
Stderr redirection unexpectedly redirects some BASH built-ins as well
I'm trying to hide all the stderr from users running an interactive BASH script but keep the errors in a log file.
However, simple stderr redirection quite unexpectedly hides some BASH output as well ...
2
votes
2answers
85 views
What were the original reason(s) for adding a “standard error” which is separate from “standard output”?
Unix provides standard output and standard error, which can be redirected independently.
$ ls /not-exist
ls: cannot access '/not-exist': No such file or directory
$ ls /not-exist > redirect.out
...
11
votes
2answers
618 views
How (and why) use stderr for both reading and writing?
According to this answer by schily, less reads navigation commands from stderr if it's not able to open /dev/tty.
This seems puzzling, since I've never seen anything write to another program's stderr ...
1
vote
1answer
233 views
Print and log stdout and stderr in fish shell
I am using the fish shell and try to log stdout and stderr into two separate files and printing them in the terminal at the same time (e.g., by piping each stream to tee).
In bash I would do (see ...
1
vote
2answers
986 views
Execute command and store everything to variable in bash
In bash script I'm developing I'm trying to execute command and capture in variable(s):
stdout
stderr
status code
how to achieve that? The command is tar, if it is of any significance.
I tried the ...
1
vote
1answer
2k views
what is the difference between >&2 and &>2 [duplicate]
Just wondering if there is any difference between:
echo "running the npm patch" >&2;
and
echo "running the npm patch" &>2;
I have actually never really understand that syntax.
0
votes
1answer
296 views
Append stderr and stdout to file
I have this:
npm install "$tgz_path" &>> "$HOME/.r2g/logs/r2g.log";
but that is syntactically incorrect.
How do I append stdout+stderr to that log file?
0
votes
1answer
46 views
stderr is being sent down pipeline but I don't want that
I have this:
echo "$some_command" | bash 2> >(prepend 'r2g-stderr:' 'red') | prepend 'r2g-stdout:' 'yellow';
What I am trying to do:
r2g-stderr: this is some stderr
r2g-stderr: this is ...
1
vote
1answer
48 views
Send stderr to a different receiver in pipe
Right now I have this:
echo "$run_test" | bash 2>&1 | prepend "r2g-test:" "yellow";
What this does is prepend "r2g-test:" to each line of the stdout/stderr.
Because I am sending stderr to ...
0
votes
1answer
43 views
SysRq output into |less, |more, |tee?
If I issue a SysRq command, how do I redirect that output (whether it is stdout or stderr is documented nowhere) to |less, |more or |tee?
2
votes
2answers
48 views
stderr redirection by reading a file [duplicate]
I read content of the file into variable like this
var=$(<somefile)
But if the file doesn't exist I get accordingly an error message
bash: somefile: No such file or directory
Is it possible to ...
0
votes
0answers
38 views
In cron, /usr/bin/paplay does not display stderr
My PC's pulse audio dies whenever I open and close virtualbox windows in a certain situation.
So I tried to monitor the audio state by crontab -e.
Usually, in the commandline, $ paplay beep.wav &...
0
votes
1answer
88 views
Redirect command error to variable in if statement
I'm creating a script and I would need to redirect the error of a command inside an if statement.
ERROR=""
if tar -xf $1 -C $2/$DIR_NAME 2> $ERROR;
then
echo "Done"
else
rm -rf $2/$...
1
vote
1answer
145 views
How to capture stderr of a bash keyword (e.g. time)?
I want to time reading bash history and put the result into a variable.
Unfortunately, time (which is a shell keyword) prints the result to stderr, and apparently redirecting stderr from shell ...
1
vote
4answers
173 views
How to make bash substitution $(<“filename”) silent
I want to replace cat:
var=$(cat "filename" 2>/dev/null)
by bashism syntax:
var=$(<"filename")
The problem is that I don't know how to make the bashism silent to avoid such warnings:
bash: ...
0
votes
2answers
55 views
Supress specific output lines of a command
I wanted to search all the files starting with chrom in /var directory. So I executed this
$ ls -R | grep "^chrom"
To my astonishment, It showed this. Few starting lines look like this :
amit@...
0
votes
2answers
97 views
How would I redirect an error from a failed if condition [closed]
I am trying to better understand STDERR and when/where to place 2> within the initial testing phase of a loop.
My script is as follows...
#!/bin/bash
file1=/tmp/file1
file2=/tmp/file2
if [ -e $...
2
votes
2answers
6k views
Ambiguous output redirect
I'm trying to redirect stderr to stdout and then out to a file in an init script, but when I introduce stderr to stdout I get the “Ambiguous output redirect” error. Stdout alone does not result in the ...
9
votes
1answer
915 views
display STDOUTs before STDERR?
I'm new to bash and I can not for the life of me figure out how to run a certain command, suppose ./fff and print regular stdouts before stderr (I'm confused about the meaning myself)
for example
$ ...
1
vote
3answers
862 views
How can I convert to uppercase stderr output but not stdout?
I'm using rsync to backup some files:
rsync -PaSh --stats --delete -e "-i key -p XXXX" "/source/" username@192.168.0.1:/destination/ 2> output.txt | grep -e 'bytes received' -e 'total bytes' -e ...
2
votes
3answers
411 views
Display console output 1 or more lines below
When I run a command like tail ~/SOMEFILE I get, for example:
testenv@vps_1:~# tail ~/SOMEFILE
This is the content of SOMEFILE.
But what if I want to have a carriage return between: testenv@...
1
vote
2answers
1k views
Redirect stdout and/or stderr to path in variable
How do I redirect stdout and/or stderr to a path I have specified in a variable? Note: I don't want to overwrite the variable itself, I want to make std[xxx] write to the file specified in the ...
4
votes
3answers
843 views
Communicate backwards in a pipe
I have a simple pipeline:
node foo.js | node bar.js
bar.js will read from stdin to get data from foo.js.
But what I want to do is ensure that bar.js gets one of the last messages from foo.js before ...
2
votes
1answer
121 views
Where does stderr go to during boot (SysVinit)?
I'm trying to diagnose some boot problems I am having with a custom linux kernel that I have configured and built. I've been digging through some of the source code for klogd, and apparently, if ...
4
votes
1answer
744 views
/dev/stderr in systemd service
I'm writing a service which should start LTE connection.
But the utility I'm using to connect (sakis3g) is writing to /dev/stderr, which is not available in systemd and the log is full of
Cannot ...
0
votes
2answers
503 views
Send stderr to stdout for purposes of grep [duplicate]
This won't work, because all the stdio will go to stderr:
webpack -w --ignore=*.js | grep ignore
so I try this:
webpack -w --ignore=*.js > grep ignore 2>&1
but that will write a file ...
0
votes
1answer
55 views
Why do colors not show up (control characters) when piping stdout/stderr on *nix systems?
Why do colors not show up (control characters) when piping stdout/stderr on *nix systems?
When I do:
foo | bar
if foo writes color encoded strings (with control chars) to stdout, they won't show up ...
1
vote
2answers
43 views
Logging only a specific part of stderr?
Couldn't find anything on this, but I'm trying to only log a specific part of stderr to a file. So for example
Running tar -xzf file 2>> log.txt, and getting an error
tar: Child returned ...
0
votes
3answers
66 views
Script error message in a single line
I am executing the command
mv /prod/new/outputlog/error.log /prod/hist/new/outputlog/error.log.32423423424
using shell script.
Since the error.log file is not available the command writing an ...
