The question starts with the premise of passing a parameter to a script call and assigning the parameter to the variable X. Consider a sample script called test.sh:
Execute the script by passing a parameter. The output from the script will look like:
EDIT:
By the way, you can get a lot of information on shell scripting from the Linux Documentation Project's guides for BASH. They are BASH specific, but many of the concepts apply to other shells as well. BASH is generally available on all *NIX systems and is arguably among the most flexible. They are located at the following URLs:
Beginners: http://tldp.org/LDP/Bash-Beginners-G...tml/index.html
Advanced: http://tldp.org/LDP/abs/html/index.html
Last edited by dunkar70; 05-08-2010 at 01:03 PM..
Reason: Adding reference
I'm having to write 'C' programs for a group of HP-UX 11.X systems. While I have found many 'C' reference books which I like, none of them reference using 'C' in the UNIX environment.
Anyone have any good recommendations for books about 'C' programming under UNIX?
Thanks.
Chris (0 Replies)
Hi all,
How can I use sed to perform a substitution if the string that I'm going to substitute is stored in a variable:
Let's say:
sed 's/abcdefg/good'
VS
tmp="abcdefg"
sed 's/$tmp/good'
The second case doesn't work. Guess it's due to the single quotes on the outside. How can I... (1 Reply)
Hi!
I need to determin the most efficient way to do something (rather simple, I thought).
I'm currently echo(ing) a series of menu options, and reading the command input as the number associated with the entry. What I need to do is when the option 1 is selected, that it references a list and... (18 Replies)
I can't seem to make what appears to be a simple substitution.
I want to define a list of systems for which daily reports need to be filed
systems="systemA systemC systemZ"
I then want to run a loop
for i in ${systems}
Analyze statistics
Create the reports
mailx (8 Replies)
Hi there,
I have included an external properties file into my BASH script via the 'source' command.
I am attempting to dynamically assign a variable in the BASH script, that references the variable name within the external properties file i.e.
#!/bin/bash
pth=${0%/*}
source... (3 Replies)
Use and complete the template provided. The entire template must be completed. If you don't, your post may be deleted!
1. The problem statement, all variables and given/known data:
i know when undefined reference shows up the program is saying it is not link to that function but the problem... (1 Reply)
Guys,
May i know how can we de reference the code reference variable.?
my $a = sub{$a=shift;$b=shift;print "SUM:",($a+$b),"\n";};
print $a->(4,5);
How can we print the whole function ?
Please suggest me regarding this.
Thanks for your time :)
Cheers,
Ranga :) (0 Replies)
Hi,
Could you please help me to get last reference date in Unix, in Unix we maintain SAS7BDAT files.
Is there any command or script to get the info,
Thank you. (2 Replies)
Discussion started by: subbarao12
2 Replies
LEARN ABOUT DEBIAN
flock
FLOCK(1) User Commands FLOCK(1)NAME
flock - manage locks from shell scripts
SYNOPSIS
flock [-sxon] [-w timeout] lockfile [-c] command...
flock [-sxon] [-w timeout] lockdir [-c] command...
flock [-sxun] [-w timeout] fd
DESCRIPTION
This utility manages flock(2) locks from within shell scripts or the command line.
The first and second forms wraps the lock around the executing a command, in a manner similar to su(1) or newgrp(1). It locks a specified
file or directory, which is created (assuming appropriate permissions), if it does not already exist.
The third form is convenient inside shell scripts, and is usually used the following manner:
(
flock -n 9 || exit 1
# ... commands executed under lock ...
) 9>/var/lock/mylockfile
The mode used to open the file doesn't matter to flock; using > or >> allows the lockfile to be created if it does not already exist, how-
ever, write permission is required; using < requires that the file already exists but only read permission is required.
By default, if the lock cannot be immediately acquired, flock waits until the lock is available.
OPTIONS -s, --shared
Obtain a shared lock, sometimes called a read lock.
-x, -e, --exclusive
Obtain an exclusive lock, sometimes called a write lock. This is the default.
-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.
-n, --nb, --nonblock
Fail (with an exit code of 1) rather than wait if the lock cannot be immediately acquired.
-w, --wait, --timeout seconds
Fail (with an exit code of 1) if the lock cannot be acquired within seconds seconds. Decimal fractional values are allowed.
-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.
-c, --command command
Pass a single command to the shell with -c.
-h, --help
Print a help message.
AUTHOR
Written by 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 ftp://ftp.kernel.org/pub/linux/utils/util-linux/.
util-linux February 2006 FLOCK(1)