James,
Space has a special meaning for the shell as a field separator and
it treats multiple spaces as one.
You have two ways of displaying the two spaces:
or
I'm reading from a file that is semi-colon delimited. One of the fields contains 2 spaces separating the first and last name (4th field in - "JOHN<space><space> DOE"):
e.g. TORONTO;ONTARIO;1 YONGE STREET;JOHN DOE;CANADA
When I read this record and either echo/print to screen or write to... (4 Replies)
Hi ,
I am currently using the while loop in bash shell, as follows.
while read line
do
echo $line
done < file.txt
However, i want to use the while loop on file.txt, which will read the file with 4 lines of gap.
Ex- if file.txt is a file of 100 lines, then i want to use the loop such... (3 Replies)
Hi all,
I'm sure this is quite a simple problem, but i'm completely new to shell scripting, so bare with me. Having problems with the read command. Here's what I have:
read -rp "Command to execute: " the_command
...
...
echo "$the_command"
...
...
eval "$the_command"
Now, say, for... (8 Replies)
our user creates a text file with a white space on the filename. this same file is transfered to unix via automation tool. i have a korn shell script that reads these files on a input directory and connects to oracle database to run the oracle procedures which will load the data from each of the... (2 Replies)
Hi Guys,
I'm a newb at shell scripting and successfully attempted a small disk space script (victory!!) but i'm wondering whether it actually takes into consideration KB,MB,GB. Please take a look at the script and advise.
##script to check if file sys has reached threshold.
... (3 Replies)
`echo $file | sed 's/ / /g'`
Hey guys I want help in converting the spaces in my file names to '\ ' .
Example:
UK maps --> UK\ maps
Could someone please help me.
I have tried the following sequences already (none of them work):
1)s/ /\ /g
2)s/ /\\ /g
3)s/ /\\\ /g
Can someone... (7 Replies)
I was wondering how I would go around to do this.
This is an example of my output
Sun Aug 21 2016 03:00:00, BLAH
Mon Aug 22 2016 03:54:00, BLAH
Tue Aug 23 2016 04:22:11, BLAH
Thu Aug 25 2016 05:00:00, BLAH
Now what I would like to do is only count CONSECUTIVE days so in the... (1 Reply)
I need to replace consecutive double quotes in a csv file, the data in the file is enclosed in double quotes but there are some places where the quotes are repeating
Example is below
Incoming data is :
"Pacific Region"|"PNG"|"Jimmy""|""|
Need output as:
"Pacific... (10 Replies)
Hi I have a .csv file and when opened in notepad looks like this
gggg,nnnn,"last,first","llll""",nnn
So, Here I would like the ouput as below
gggg,nnnn,"last,first","llll",nnn
i.e replace all two double quotes into one. How could I do that?
This file is being processed by another... (5 Replies)
Discussion started by: dnat
5 Replies
LEARN ABOUT OPENDARWIN
shlock
SHLOCK(1) BSD General Commands Manual SHLOCK(1)NAME
shlock -- create or verify a lock file for shell scripts
SYNOPSIS
shlock -f lockfile [-p PID] [-u] [-v]
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 rename(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 -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.
The -v option causes shlock to be verbose about what it is doing.
RETURN VALUES
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 filesystem where the lock file is to be created is writeable 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.
AUTHOR
Erik E. Fair <fair@clock.org>
BUGS
Does not work on NFS or other network filesystem 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