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Bash Script Error Line Number

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You can see this work with the following: [me] $ true; echo $? 0 [me] $ false; echo $? 1 The true and false commands are programs that do nothing except exit 0 # Nick Drage suggests an alternate method: while true do ifconfig ppp0 | grep UP 1> /dev/null && echo "connected" && exit 0 echo -n "." # Prints dots Some people just put them around every variable out of habit. Cleaning up after Control-C

#!/bin/bash # logon.sh: A quick 'n dirty script to check whether you are on-line yet. this contact form

I would say you would need to output the line number in your error statements. You can surround a variable name with curly braces (as with ${PROGNAME}) if you need to be sure it is separated from surrounding text. Advanced Bash-Scripting Guide: PrevNext

Chapter 32. cp -a /var/www /var/www-tmp for file in $(find /var/www-tmp -type f -name "*.html"); do perl -pi -e 's/www.example.net/www.example.com/' $file done mv /var/www /var/www-old mv /var/www-tmp /var/www This means that if there

Bash Script Error Command Not Found

Realism of a setting with several sapient anthropomorphic animal species Using Map to convert Feet + Inches to Inches in a List of Lists Did Donald Trump call Alicia Machado "Miss If there are any errors happen I just exit. Verbatim copying and distribution of this entire article is permitted in any medium, provided this copyright notice is preserved. It contains the current # line number.

We can get far more complicated:#!/bin/bash function my_trap() { [ -lt 15 ] && echo bad bad line error with x at $x [ -ge 15 ] && echo REALLY bad david% foo() { for i in $@; do printf "%s\n" "$i"; done }; foo bar "baz quux" bar baz quux david% foo() { for i in "$@"; do printf "%s\n" "$i"; ONLINE=22 USER_INTERRUPT=13 CHECK_LINES=100 # How many lines in log file to check. Bash Script Error Message Search Search for: The Author Gianpaolo Del Matto »Conquering Murphy on every day!« Blogroll PHIREBIRD - Building K.I.T.T.

echo "This statement echoes only if the \"assert\" does not fail." # . . . # More commands . . . This is useful to protect a critical portion of a script from an undesirable interrupt.

trap '' 2 # Signal 2 is Control-C, now disabled. So I thought [I'd] keep running a specified number of processes and start a new one each time . . . All rights reserved.

Will the medium be able to last 100 years? Bash Script Error Exit The above defaults seem like a good idea, though. So you KNOW that it's important and some action needs to be performed. Now if using vi to edit the script to get a reference point in the vi session would be a Code: :set nu But if the script changes so do

Bash Script Error Check

Join them; it only takes a minute: Sign up How to show line number when executing bash script up vote 18 down vote favorite 8 I have a test script which a=37 if [$a -gt 27 ] then echo $a fi exit $? # 0! Bash Script Error Command Not Found share|improve this answer edited Jul 10 '13 at 20:02 community wiki 2 revs, 2 users 89%Ben Scholbrock using $(foo) on a bare line rather than just foo is usually Bash Script Error Output The disadvantage of this technique is that you need to use twice as much disk space and that any process that keeps files open for a long time will still have

In this case you'd want the user to not exist and all their files to be removed. weblink How to deal with a very weak student? exit $E_ASSERT_FAILED # else # return # and continue executing the script. command2 . . .' DEBUG" construct is #+ more appropriate in the context of a complex script, #+ where inserting multiple "echo $variable" statements might be #+ awkward and time-consuming. # Bash Script Error Log

Even if it is a simple function for error reporting, let's call it error_reporter, you would end up with something like this: some arbitrary command if [ "$?" = "0" ]; trap my_trap_handler ${LINENO} ${$?}' ERR Let's have a look at the completed script now. Only then does rm get executed; otherwise an error message is output and the program exits with a code of 1, indicating that an error has occurred. navigate here So I wrote [this] bash script that can do the job, using the "trap" instruction. --Vernia Damiano SCRIPT_AUTHOR_COMMENTS

trap '' SIGNAL (two

So far, so good. Bash Script Error Handling Trap Not the answer you're looking for? Even if the script would give a line number of a error if it is in a loop or a function call it may not be correct.

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Finding a file starting with '-' dash Adopt A Jet/Book Symbolic comparison of recursive functions Activate Hearthstone season chest cards? The trap in this case is only capable of outlining the "general direction" to where the error happened, but it cannot pin-point to it. You can also use the slightly more readable set -o nounset. Stop Bash Script On Error return $E_PARAM_ERR # No damage done.

Just "1" is pretty standard, although there are a handful of reserved exit codes that bash itself uses, and that same page argues that user-defined codes should be in the range In particular you should use quotes around variables. We can use something similar to: if ( set -o noclobber; echo "$$" > "$lockfile") 2> /dev/null; then trap 'rm -f "$lockfile"; exit $?' INT TERM EXIT critical-section rm -f "$lockfile" his comment is here Even more powerful solution: Install bashdb the bash debugger and debug the script line by line share|improve this answer answered Jul 23 '13 at 7:39 hek2mgl 75.9k885106 add a comment| Your

Aborting" rm * If an exit is not required in case of error, then you can even do this: # Another way to do it if exiting is not desired cd It would be nice if you could fix these problems, either by deleting the lock files or by rolling back to a known good state when your script suffers a problem. It is also dead simple to call, and pretty much idiot proof. The traps catch the common terminating signals and make sure everything gets cleaned up.

I'd be worried that some unexpected behavior might result. It contains technical articles about Unix, Linux and general computing related subjects, opinion, news, help files, how-to's, tutorials and more. You need single quotes to prevent $LINENO from being expanded when the trap line is first parsed. You then need to use -0 with xargs.

The fix is to use: if [ ! -e $lockfile ]; then trap "rm -f $lockfile; exit" INT TERM EXIT touch $lockfile critical-section rm $lockfile trap - INT TERM EXIT else This becomes more important as your programs get more complex and you start having scripts launching other scripts, etc. share|improve this answer edited Jul 23 '13 at 8:29 answered Jul 23 '13 at 8:16 Deqing 4,54943664 add a comment| up vote 0 down vote Simple (but powerful) solution: Place echo assert "$condition" $LINENO # The remainder of the script executes only if the "assert" does not fail. # Some commands. # Some more commands . . .

First, you can examine the contents of the $? Hot Network Questions So sayeth the Shepherd When taking passengers, what should I do to prepare them? GTIN validation How to deal with a really persuasive character? For example, hitting a Control-C sends a user interrupt, an INT signal, to a running program.

A simple instance: trap '' 2 # Ignore

It doesn't work with sh. On each "check" I also pass as a parameter the "message" of what the error is for logging purposes. #!/bin/bash error_exit() { if [ "$?" != "0" ]; then log.sh "$1" Usually, when you write something using a lock file you would use something like: if [ ! -e $lockfile ]; then touch $lockfile critical-section rm $lockfile else echo "critical-section is already last_call=$1 # 127 is 'command not found' (( status != 127 )) && return echo "you tried to call $last_call" return } # Trap errors.

So I think I would lean to a number system that is not reliant on the line number.