mmmmm you're right the exit should follow
I've just tested it using this
It DOES work and exits WITHOUT displaying
my debugging info was
btw my machine details are Linux fhinux 2.6.5-7.191-default #1 Tue Jun 28 14:58:56 UTC 2005 i686 i686 i386 GNU/Linux
i downloaded a text file from metalab.unc.edu called sh.txt and in this reference manual it refers to shell scripting exit status .. at the end of one of the examples that author gave an exit status of 127..
to what does a 127 exit status refer too and what is its purpose in the code.
moxxx68 (1 Reply)
I hope one of you smart people out there can help me with what seems like a real simple questing but I can't quite figure out.
In a script I am doing a cmp on two files. I am trying to check the exit status with an if statement but can't seem to figure out the syntax. If the exit status is 1 I... (4 Replies)
Hi guys,
I'm new to unix but loving it!! BUT this is driving me nuts as i can't work out the best way to do it.
I have a while true loop that i use to monitor something. For my own reasons in ths script i have disabled the CTRL C using the trap command. But i want to put in a option to exit... (5 Replies)
Hi all,
I'm running a program which return 1 upon success.
But when encounters problem shell return 's '1' .
How to differentiate between them the shell return value and script return value.
Ex. function fn return '1' if executed successfully and '0' if failed. But when if shell encounters... (1 Reply)
I'm preparing for exam and one of exams is to write own test command...
I wonder if in unix is a command which just returns exit code you specify..
I know I can easily write a function like this:
exStatus() {
return $1
}
-> my question is rather theoretical
thank you! (9 Replies)
I have a shell script (#!/bin/sh) that interacts with Appworx and Banner Admin. In my script I want to check the exit status of awrun before continuing. awrun can run for 10 seconds or it can run for over a minute. So my question is, will it go through my if statement before awrun may even be... (2 Replies)
Hi ,
I have a bash script , which does the network configuration. Messages from this script are dumped on console as well as stored in a log file .
This script is invoked from a C code using system call . The script returns different exit code , to indicate different error cases. The... (1 Reply)
Hi All,
I am trying to create a zip file with all the txt files(these are in large number) in the current directory. I am able to do this operation sucessfully.
After this i want to get the status of the tar command executed and do accordingly. When i am trying with the below code, the status... (3 Replies)
I'm extremely new to shell scripting so I apologize for the crudeness of my descriptions. I am editing a script that will write files (e.g. Job0_A.com, Job1_A.com, etc.) and then run them through a program called gaussian (computational chemistry program). The script will then take the output files... (10 Replies)
Hi all,
I am trying to use a script (a.sh) which is calling another script(b.sh).
And I want to use the exit code(set by me) of b.sh in a.sh.
I am using this in b.sh
#!/bin/sh
<-- code -->
if ; then
exit 0
else
exit 1
fiBut... (2 Replies)
Discussion started by: Raj999
2 Replies
LEARN ABOUT PLAN9
flock
FLOCK(1) User Commands FLOCK(1)NAME
flock - manage locks from shell scripts
SYNOPSIS
flock [options] file|directory command [arguments]
flock [options] file|directory -c command
flock [options] number
DESCRIPTION
This utility manages flock(2) locks from within shell scripts or from the command line.
The first and second of the above forms wrap the lock around the execution of a command, in a manner similar to su(1) or newgrp(1). They
lock a specified file or directory, which is created (assuming appropriate permissions) if it does not already exist. By default, if the
lock cannot be immediately acquired, flock waits until the lock is available.
The third form uses an open file by its file descriptor number. See the examples below for how that can be used.
OPTIONS -c, --command command
Pass a single command, without arguments, to the shell with -c.
-E, --conflict-exit-code number
The exit code used when the -n option is in use, and the conflicting lock exists, or the -w option is in use, and the timeout is
reached. The default value is 1.
-F, --no-fork
Do not fork before executing command. Upon execution the flock process is replaced by command which continues to hold the lock.
This option is incompatible with --close as there would otherwise be nothing left to hold the lock.
-e, -x, --exclusive
Obtain an exclusive lock, sometimes called a write lock. This is the default.
-n, --nb, --nonblock
Fail rather than wait if the lock cannot be immediately acquired. See the -E option for the exit code used.
-o, --close
Close the file descriptor on which the lock is held before executing command. This is useful if command spawns a child process
which should not be holding the lock.
-s, --shared
Obtain a shared lock, sometimes called a read lock.
-u, --unlock
Drop a lock. This is usually not required, since a lock is automatically dropped when the file is closed. However, it may be
required in special cases, for example if the enclosed command group may have forked a background process which should not be hold-
ing the lock.
-w, --wait, --timeout seconds
Fail if the lock cannot be acquired within seconds. Decimal fractional values are allowed. See the -E option for the exit code
used. The zero number of seconds is interpreted as --nonblock.
--verbose
Report how long it took to acquire the lock, or why the lock could not be obtained.
-V, --version
Display version information and exit.
-h, --help
Display help text and exit.
EXAMPLES
shell1> flock /tmp -c cat
shell2> flock -w .007 /tmp -c echo; /bin/echo $?
Set exclusive lock to directory /tmp and the second command will fail.
shell1> flock -s /tmp -c cat
shell2> flock -s -w .007 /tmp -c echo; /bin/echo $?
Set shared lock to directory /tmp and the second command will not fail. Notice that attempting to get exclusive lock with second
command would fail.
shell> flock -x local-lock-file echo 'a b c'
Grab the exclusive lock "local-lock-file" before running echo with 'a b c'.
(
flock -n 9 || exit 1
# ... commands executed under lock ...
) 9>/var/lock/mylockfile
The form is convenient inside shell scripts. The mode used to open the file doesn't matter to flock; using > or >> allows the lock-
file to be created if it does not already exist, however, write permission is required. Using < requires that the file already
exists but only read permission is required.
[ "${FLOCKER}" != "$0" ] && exec env FLOCKER="$0" flock -en "$0" "$0" "$@" || :
This is useful boilerplate code for shell scripts. Put it at the top of the shell script you want to lock and it'll automatically
lock itself on the first run. If the env var $FLOCKER is not set to the shell script that is being run, then execute flock and grab
an exclusive non-blocking lock (using the script itself as the lock file) before re-execing itself with the right arguments. It
also sets the FLOCKER env var to the right value so it doesn't run again.
EXIT STATUS
The command uses sysexits.h return values for everything, except when using either of the options -n or -w which report a failure to
acquire the lock with a return value given by the -E option, or 1 by default.
When using the command variant, and executing the child worked, then the exit status is that of the child command.
AUTHOR
H. Peter Anvin <hpa@zytor.com>
COPYRIGHT
Copyright (C) 2003-2006 H. Peter Anvin.
This is free software; see the source for copying conditions. There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICU-
LAR PURPOSE.
SEE ALSO flock(2)AVAILABILITY
The flock command is part of the util-linux package and is available from Linux Kernel Archive <https://www.kernel.org/pub/linux/utils
/util-linux/>.
util-linux July 2014 FLOCK(1)