Linux Bash Error Variable
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Bash If Exit Code
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Bash Script Exit On Error
you, helping each other. Join them; it only takes a minute: Sign up How to store standard error in a variable in a Bash script up vote 88 down vote favorite 35 Let's say I have a script
Linux Exit Code
like the following: useless.sh echo "This Is Error" 1>&2 echo "This Is Output" And I have another shell script: alsoUseless.sh ./useless.sh | sed 's/Output/Useless/' I want to capture "This Is Error", or any other stderr from useless.sh, into a variable. Let's call it ERROR. Notice that I am using stdout for something. I want to continue using stdout, so redirecting stderr into stdout is not helpful, in this case. So, basically, I want to do linux exit codes ./useless.sh 2> $ERROR | ... but that obviously doesn't work. I also know that I could do ./useless.sh 2> /tmp/Error ERROR=`cat /tmp/Error` but that's ugly and unnecessary. Unfortunately, if no answers turn up here that's what I'm going to have to do. I'm hoping there's another way. Anyone have any better ideas? bash shell redirect variables stderr share|improve this question edited Apr 4 '12 at 7:56 l0b0 19.8k660118 asked Jun 7 '09 at 16:38 psycotica0 7021711 3 What exactly to want to use stdout for? Do you simply want to view it on the console? Or are you capturing/redirecting it's output? If it's just to the console you redirect stdout to console and stderr to stdout to capture it: ERROR=$(./useless.sh | sed 's/Output/Useless/' 2>&1 1>/dev/ttyX) –Tim Kersten Mar 23 '11 at 11:41 add a comment| 10 Answers 10 active oldest votes up vote 41 down vote accepted It would be neater to capture the error file thus: ERROR=$( ou
exit codes, exit codes are important and this article describes how to use them in your scripts and understand them in general. Written by Benjamin Cane on 2014-09-02 14:45:00| 4 min read Sponsored by Lately I've been working exit bash shell on a lot of automation and monitoring projects, a big part of these projects are taking bash return value from function existing scripts and modifying them to be useful for automation and monitoring tools. One thing I have noticed is sometimes scripts use exit codes bash not equal and sometimes they don't. It seems like exit codes are easy for poeple to forget, but they are an incredibly important part of any script. Especially if that script is used for the command line. What are exit codes? http://stackoverflow.com/questions/962255/how-to-store-standard-error-in-a-variable-in-a-bash-script On Unix and Linux systems, programs can pass a value to their parent process while terminating. This value is referred to as an exit code or exit status. On POSIX systems the standard convention is for the program to pass 0 for successful executions and 1 or higher for failed executions. Why is this important? If you look at exit codes in the context of scripts written to be used for the command line the answer is very simple. Any http://bencane.com/2014/09/02/understanding-exit-codes-and-how-to-use-them-in-bash-scripts/ script that is useful in some fashion will inevitably be either used in another script, or wrapped with a bash one liner. This becomes especially true if the script is used with automation tools like SaltStack or monitoring tools like Nagios, these programs will execute scripts and check the status code to determine whether that script was successful or not. On top of those reasons, exit codes exist within your scripts even if you don't define them. By not defining proper exit codes you could be falsely reporting successful executions which can cause issues depending on what the script does. What happens if I don't specify an exit code In Linux any script run from the command line has an exit code. With Bash scripts, if the exit code is not specified in the script itself the exit code used will be the exit code of the last command run. To help explain exit codes a little better we are going to use a quick sample script. Sample Script: #!/bin/bash touch /root/test echo created file The above sample script will execute both the touch command and the echo command. When we execute this script (as a non-root user) the touch command will fail, ideally since the touch command failed we would want the exit code of the script to indicate failure with an appropriate exit code. To check the exit code we can simply print th
here for a quick overview of the site Help Center Detailed answers to any questions you might have Meta Discuss the workings and policies of this site About http://unix.stackexchange.com/questions/132511/how-to-capture-error-message-from-executed-command Us Learn more about Stack Overflow the company Business Learn more about hiring developers http://unix.stackexchange.com/questions/207957/assigning-exit-code-to-a-shell-local-variable or posting ads with us Unix & Linux Questions Tags Users Badges Unanswered Ask Question _ Unix & Linux Stack Exchange is a question and answer site for users of Linux, FreeBSD and other Un*x-like operating systems. Join them; it only takes a minute: Sign up Here's how it works: Anybody can ask a exit code question Anybody can answer The best answers are voted up and rise to the top How to capture error message from executed command? up vote 5 down vote favorite 1 I was tasked to create an automated server hardening script and one thing that they need is a report of all the output of each command executed. I want to store the error message inside a string and append linux exit code it in a text file. Let's say I ran this command: /sbin/modprobe -n -v hfsplus The output of running this in my machine would be: FATAL: Module hfsplus not found How can I store that error message inside a string? Any help would be greatly appreciated. Thanks! bash scripting string share|improve this question asked May 29 '14 at 7:25 Miguel Roque 1173412 I tried running this command: var=$(/sbin/modprobe -n -v hfsplush) And then displaying it: $var But it still doesn't capture the error message inside the string. –Miguel Roque May 29 '14 at 7:42 add a comment| 4 Answers 4 active oldest votes up vote 10 down vote you can do it by redirecting errors command: /sbin/modprobe -n -v hfsplus 2> fileName as a script #!/bin/bash errormessage=$( /sbin/modprobe -n -v hfsplus 2> &1) echo $errormessage or #!/bin/bash errormessage=`/sbin/modprobe -n -v hfsplus 2> &1 ` echo $errormessage if you want to append the error use >> instead of > share|improve this answer edited May 29 '14 at 7:48 answered May 29 '14 at 7:42 Networker 4,74462856 I've tried that approach and it stores it DIRECTLY in the text file. I want it to store inside a string first so
here for a quick overview of the site Help Center Detailed answers to any questions you might have Meta Discuss the workings and policies of this site About Us Learn more about Stack Overflow the company Business Learn more about hiring developers or posting ads with us Unix & Linux Questions Tags Users Badges Unanswered Ask Question _ Unix & Linux Stack Exchange is a question and answer site for users of Linux, FreeBSD and other Un*x-like operating systems. Join them; it only takes a minute: Sign up Here's how it works: Anybody can ask a question Anybody can answer The best answers are voted up and rise to the top Assigning exit code to a shell local variable up vote 11 down vote favorite 2 #!/bin/bash function0() { local t1=$(exit 1) echo $t1 } function0 echo prints empty value. I expected: 1 Why doesn't t1 variable get assigned the exit command's return value - 1? bash shell variable command-substitution share|improve this question edited Jun 6 '15 at 18:43 Gilles 372k696761127 asked Jun 6 '15 at 15:06 Madhavan Kumar 1,1282927 add a comment| 3 Answers 3 active oldest votes up vote 19 down vote accepted local t1=$(exit 1) tells the shell to: run exit 1 in a subshell; store its output (as in, the text it outputs to standard output) in a variable t1, local to the function. It's thus normal that t1 ends up being empty. ($() is known as command substitution.) The exit code is always assigned to $?, so you can do function0() { (exit 1) echo "$?" } to get the effect you're looking for. You can of course assign $? to another variable: function0() { (exit 1) local t1=$? echo "$t1" } share|improve this answer edited Jun 7 '15 at 16:09 answered Jun 6 '15 at 15:13 Stephen Kitt 42.5k56494 You know, you can always put the return into the pipe, too. `$(trap 'printf "::ERRNO:$?"' 0; # now do whatever however - that trap will ensure the last string written is the last return for the whole substitution context. –mikeserv Jun 7 '15 at 16:28 add a comment| up vote 6 down vote Exit code was stored in $? variable. Using Command Substitution only captur