Hello,
I'm trying to write a script that checks for previous instances of the same script which may still be running (this script is scheduled to run every 30 minutes). I want to somehow use the pid from each instance to make sure the previous one isn't running before continuing with my... (5 Replies)
Hello all,
I currently connect to several servers multiple times a day. Most of the time I connect via SSH through the terminal emulator poderosa (my personal favorite), but sometimes I connect via telnet through xstart because I need it to export a GUI.
What I want to do is add something to... (3 Replies)
I currently run a script over a vpnc tunnel to back-up my data to a remote server. However for a number of reasons the tunnel often collapses. If I manually restore the tunnel then the whole thing can continue, but I want to add into my script a section whereby while the transfer is taking place,... (8 Replies)
Hi all,
I encountered a problem where my script stops running the remaining checks after becoming an admin that is written within the script.
For example:
=========================================
#!/bin/sh
check 1 # Runs successfully
check 2 # Runs successfully
/com/bin/admin #... (1 Reply)
I'm working on a script (mostly for practice) to simplify a task I have to do every now and then. I have a cluster with 6 servers on it, each server has a directory with a set of files called *.pid and *.mpid. Each file contains the pid of a process that may or may not be running on that server.... (3 Replies)
Hi.
I'm triyng to make a Bash Script that checks (recursively) the MD5 from all the files in a certain directory and compare them against some other check that should be already done and saved in a file.
I've reached to the point where i have the MD5 from the file and the MD5 that the script... (1 Reply)
I an using the below functions in my script.
---------
checkRT()
{
subHeader "Runtime Check"
for nn in `cat $HOST_FILE|egrep -i 'msdp|ca|backup|db'|grep -v '#'|sed '/^$/d'|awk '{ print $1":"$2":"$3}'`
do
fhba=`expr $nn|cut -d: -f2`
fhba2=`expr $nn|cut -d: -f3`
subSubHeader $fhba2
ssh... (1 Reply)
Hi ,
I need a script which performs below activity
I have one file named "testfile" in 9 different directories with same name.
I want to perform below action with each testfile of each directory.
if ; then
mv listfiles listfiles_`date +%b%y`
else
echo No Such files
fi
... (4 Replies)
Hi ,
I need a script for processing below scenario.
I have to check daily by doing ftp IP to check it is logging or not.
So i want this activity to be automated such that if login succesful i will get "FTP LOGIN SUCCESS" in a log file and if fails i want the error message in the same log... (1 Reply)
Hello everyone,
I was wondering if any of you could help me with this. I am an absolute beginner and don't know how to program, but I can follow a tutorial and tweak code sometimes. My understanding of programing is limitted to what for and while loops do, and how if then else logic works. That... (2 Replies)
Discussion started by: tomeurp
2 Replies
LEARN ABOUT MOJAVE
shlock
SHLOCK(1) BSD General Commands Manual SHLOCK(1)NAME
shlock -- create or verify a lock file for shell scripts
SYNOPSIS
shlock [-du] [-p PID] -f lockfile
DESCRIPTION
The shlock command can create or verify a lock file on behalf of a shell or other script program. When it attempts to create a lock file, if
one already exists, shlock verifies that it is or is not valid. If valid, shlock will exit with a non-zero exit code. If invalid, shlock
will remove the lock file, and create a new one.
shlock uses the link(2) system call to make the final target lock file, which is an atomic operation (i.e. "dot locking", so named for this
mechanism's original use for locking system mailboxes). It puts the process ID ("PID") from the command line into the requested lock file.
shlock verifies that an extant lock file is still valid by using kill(2) with a zero signal to check for the existence of the process that
holds the lock.
The -d option causes shlock to be verbose about what it is doing.
The -f argument with lockfile is always required.
The -p option with PID is given when the program is to create a lock file; when absent, shlock will simply check for the validity of the lock
file.
The -u option causes shlock to read and write the PID as a binary pid_t, instead of as ASCII, to be compatible with the locks created by
UUCP.
EXIT STATUS
A zero exit code indicates a valid lock file.
EXAMPLES
BOURNE SHELL
#!/bin/sh
lckfile=/tmp/foo.lock
if shlock -f ${lckfile} -p $$
then
# do what required the lock
rm ${lckfile}
else
echo Lock ${lckfile} already held by `cat ${lckfile}`
fi
C SHELL
#!/bin/csh -f
set lckfile=/tmp/foo.lock
shlock -f ${lckfile} -p $$
if ($status == 0) then
# do what required the lock
rm ${lckfile}
else
echo Lock ${lckfile} already held by `cat ${lckfile}`
endif
The examples assume that the file system where the lock file is to be created is writable by the user, and has space available.
HISTORY
shlock was written for the first Network News Transfer Protocol (NNTP) software distribution, released in March 1986. The algorithm was sug-
gested by Peter Honeyman, from work he did on HoneyDanBer UUCP.
AUTHORS
Erik E. Fair <fair@clock.org>
BUGS
Does not work on NFS or other network file system on different systems because the disparate systems have disjoint PID spaces.
Cannot handle the case where a lock file was not deleted, the process that created it has exited, and the system has created a new process
with the same PID as in the dead lock file. The lock file will appear to be valid even though the process is unrelated to the one that cre-
ated the lock in the first place. Always remove your lock files after you're done.
BSD June 29, 1997 BSD