@RudiC, your code runs perfect, but why I am insisting in bash script is because I have worked on it for some time so know the basics of it and later on I can automate this stuff using a script, with others also using it. My code is just a simple print statement, so its not even worth reading it out. Thats the reason I never posted it at the start.
@drysdalk, your script is giving me an error -> no such file or directory. I had created the example.txt beforehand. Just to let you know, I have rights only under my directory so have altered the script code accordingly. Other than that, you have entered the BEGIN and END using a fixed length string, which will work fine in this case but what should I do if the BEGIN and END strings are shorter or longer in length. That was the reason I was looking into using regex.
Can someone explain the following? I can use find on *.pm without quotes, but find on *.pl makes on error, I need quotes for the second version. What's up with that?
$find -name *.pm
./tieProxyStatus/Status.pm
$find -name *.pl
find: paths must precede expression
Usage: find
$find... (2 Replies)
i would like to ask how to make a script that in evry 3 lines of my paragraph(below) it would appear like this:
$ cat myparagraph
this is line 1
this is line 2
this is line3
this is line 4
this is 5
this 6
this is 7
this 8
====================================================
$ cat... (2 Replies)
I]hi all
i am in confusion since last 2 days :(
i posted thraed yesterday and some friends did help but still i couldnt get solution to my problem
let it be very clear
i have a long log file of alkatel switch and i have to seperate the minor major and critical alarms shown by ! , !! and !!!... (6 Replies)
Hi ,
Unix.com has been life saver for me I admit :)
I am trying to extract a paragraph based on matching pattern "CREATE TABLE " from a ddl file . The paragraphs are seperated by blank line .
Input file is
#cat zip.20080604.sql1
CONNECT TO TST103
SET SESSION_USER OPSDM002
... (2 Replies)
Hi All,
I want to run 5 `ps -ef | grep ` cmds in one script and i want the script to give me return code 0 if everything is OK. If it notices one of the processes is not there, it will prompt me the process name and advice me to check it.
I've wrote a script that separates the output but I want... (2 Replies)
Hello
I am trying to generate a script to run on worldwide firewalls.
I need the spf block for large sites like google, etc so I can essentially whitelist google sites for users.
(Google here is just an example...)
Right now I am just testing Bash oneliners to see how I can isolate the... (1 Reply)
Hi all,
The following lines are taken from a long paragraph:
Labels of output orbitals: RY* RY* RY* RY* RY* RY*
1\1\GINC-COMPUTE-1-3\SP\UB3LYP\6-31G\C2H5Cr1O1(1+,5)\LIUZHEN\19-Jan-20
10\0\\# ub3lyp/6-31G pop=(nbo,savenbo) gfprint\\E101GECP\\1,5\O,0,-1.7
... (1 Reply)
i'm trying to write a bash script that that will automatically extract zip files after the download.
i writed this script
#!/bin/bash
wget -c https://github.com/RonGokhle/kernel-downloader/zipball/master
CURRENDIR=/home/kernel-downloader
cd $CURRENDIR
rm $CURRENDIR/zipfiles 2>/dev/null
... (2 Replies)
I am using OSX. I have a multi-mol2 file (text file with coordinates and info for several molecules). An example of two molecules in the file is given below for molecule1 and molecule 2. The total file contains >50,000 molecules.
I would like to extract out and write to another file only the... (2 Replies)
Hello:
Have a very annoying problem:
Need to extract paragraphs with a specific string in them from a very large file
with a repeating record separator.
Example data: a file called test.out
CREATE VIEW view1
AS something
FROM table1 ,table2 as A, table3 (something FROM table4)
FROM... (15 Replies)
Discussion started by: delphys
15 Replies
LEARN ABOUT V7
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)