05-19-2009
Exclamation point in Bash
Here is a script using egrep that extracts the last word in each line:
egrep -o " [a-zA-Z'-]+[,:.!';?]*$" File.txt > Results.txt
If it is placed in a file with the requisite header:
#!/bin/bash
it works perfectly.
If on the other hand, one attempts it from the command line, one gets the following error:
-bash: !': event not found
The problem is the exclamation point in the regexp.
I have tried numerous ways to get it to work from the command line and failed: using single quotes, escaping the !, etc.
Nothing works.
Now, you may ask, if it works from a file, why insist on doing it from the command line? You're right. I shouldn't. And my research indicates that this problem is particularly annoying in bash and that people simply recommend using a different shell.
But can it be solved?
Thanks in advance...
10 More Discussions You Might Find Interesting
1. Shell Programming and Scripting
Hi,
I am trying to compare 2 floating point numbers 0.8 and 0.15 using bash and get the largest of the two. Can anyone advise. (2 Replies)
Discussion started by: borncrazy
2 Replies
2. Shell Programming and Scripting
Hi, guys,
today, I have copied a simple script which runs correctly on a computer to another one. But, the latter informs me:
Floating point exception!
@ ./command_module a b c
where command_module is the module compiled by myself.
So, I have fixed it by following steps:
1.... (5 Replies)
Discussion started by: mapleleaves
5 Replies
3. Shell Programming and Scripting
Dear all,
I have the following question. Let's say that I have the following script
#!/bin/bash
value=0.4987865
a=` printf "%6.2f" $value `
b=`echo $value + $value | bc -l`
echo $a
echo $b
exit
And the exit is:
0,00
.9975730
Thus, the problem is that the printf order does not... (2 Replies)
Discussion started by: josegr
2 Replies
4. Shell Programming and Scripting
Hello, I have an output like
Interface Chipset Driver wlan0 Intel 4965/5xxx iwlagn - and I want to take only the 'wlan0' string. This can be done by
a="Interface Chipset Driver wlan0 Intel 4965/5xxx iwlagn - "
b=${a:25:6}
echo $bThe thing is that wlan0 can be something else, like eth0 or... (2 Replies)
Discussion started by: hakermania
2 Replies
5. Shell Programming and Scripting
Hey again,
I have a basic regex that tests if a number is a float.
Thank you. (5 Replies)
Discussion started by: whyte_rhyno
5 Replies
6. UNIX for Advanced & Expert Users
What is the deal with explanation point in bash? I thought only dollar sign ($), the back-tick (`) and the backslash (\) were special in double quotes. Can someone please explain what is going on here? Why do I have to use single quotes or backslash the "!"?
$ vlc "/media/Part... (4 Replies)
Discussion started by: cokedude
4 Replies
7. Shell Programming and Scripting
Hello Everyone,
I am currently working on a script to calculate optimal tcp window size
the formula that I am following is
2 x (bandwith speed /8 * Round Trip Time ) = x
This is what I have so far
#!/bin/bash
echo "Enter connection speed" << Get the speed of the Connection from... (3 Replies)
Discussion started by: bmfmancini
3 Replies
8. Shell Programming and Scripting
Heyas
I have a script (vhs - video handler script, using ffmpeg) to encode videos.
It also encodes a dvd, but until now just non-copy-protected ones, so i've tried to add/implement a vobcopy wrapper to be used by my script.
At first it looked quite fine, but when changing from the first VOB... (9 Replies)
Discussion started by: sea
9 Replies
9. Shell Programming and Scripting
Hello,
I have often found bash to be difficult when it comes to floating point numbers. I have data with rows of tab delimited floating point numbers. I need to find the smallest number in each row that is not 0.0. Numbers can be negative and they do not come in any particular order for a given... (9 Replies)
Discussion started by: LMHmedchem
9 Replies
10. Shell Programming and Scripting
I have the following code snippet in bash
if ]; then
minm=`echo "$diff" | bc`
fi
It works well for most of the cases. However lets say diff is -0.17 and minm is -0.0017. In such a case the comparison seems to fail. Is the correct way to compare a mixture of positive and... (12 Replies)
Discussion started by: ngabrani
12 Replies
LEARN ABOUT X11R4
libbash
LIBBASH(7) libbash Manual LIBBASH(7)
NAME
libbash -- A bash shared libraries package.
DESCRIPTION
libbash is a package that enables bash dynamic-like shared libraries. Actually its a tool for managing bash scripts whose functions you may
want to load and use in scripts of your own.
It contains a 'dynamic loader' for the shared libraries ( ldbash(1)), a configuration tool (ldbashconfig(8)), and some libraries.
Using ldbash(1) you are able to load loadable bash libraries, such as getopts(1) and hashstash(1). A bash shared library that can be loaded
using
ldbash(1) must answer 4 requirments:
1. It must be installed in $LIBBASH_PREFIX/lib/bash (default is /usr/lib/bash).
2. It must contain a line that begins with '#EXPORT='. That line will contain (after the '=') a list of functions that the library
exports. I.e. all the function that will be usable after loading that library will be listed in that line.
3. It must contain a line that begins with '#REQUIRE='. That line will contain (after the '=') a list of bash libraries that are
required for our library. I.e. every bash library that is in use in our bash library must be listed there.
4. The library must be listed (For more information, see ldbashconfig(8)).
Basic guidelines for writing library of your own:
1. Be aware, that your library will be actually sourced. So, basically, it should contain (i.e define) only functions.
2. Try to declare all variables intended for internal use as local.
3. Global variables and functions that are intended for internal use (i.e are not defined in '#EXPORT=') should begin with:
__<library_name>_
For example, internal function myfoosort of hashstash library should be named as
__hashstash_myfoosort
This helps to avoid conflicts in global name space when using libraries that come from different vendors.
4. See html manual for full version of this guide.
AUTHORS
Hai Zaar <haizaar@haizaar.com>
Gil Ran <ril@ran4.net>
SEE ALSO
ldbash(1), ldbashconfig(8), getopts(1), hashstash(1) colors(1) messages(1) urlcoding(1) locks(1)
Linux Epoch Linux