Programming :: Get String From System Command Output ?
May 15, 2010I have found this from a site [url]
Code:
But it does not work for me, segfault.
I have found this from a site [url]
Code:
But it does not work for me, segfault.
I've been trying to understand pthread in C a little better. So I made a simple program that takes in a string from the command line and creates a thread to print the string. I've looked online and copied the basic concepts but there are something things I'm confused about. The programs works just fine, but I have questions. Here's what I have so far.
[Code]....
One thing I'd like to know is why the 3rd argument in the pthread_create function which is my SendMessage function needs to be typecasted to a void pointer and then send the address of the function. Also as for the 4th argument, I would see typecasting to void pointer in some of the pthread examples I saw online, but in my case I'm passing a char pointer, would this be correct? In which case would I ever want to pass a void pointer?
Do I need a pthread_exit(NULL) in my main and in the SendMessage function? If so, why? I added the sleep() function so that I could let the pthread_exit function in my SendMessage function execute first. I simply saw that the online examples on pthread had pthread_exit() in both locations.
why isnt this working as i am expecting:
Code:
[schneidz@hyper temp]$ cat example.tmp
hello world
[code]....
The below program is giving unpredictable and wrong output when I compile with g++ under Ubuntu OS , tried with the complier avilable with Ubuntu 8.04 and Ubuntu 10.04 LTS.
But it works fine when complied and ran Redhat g++ 3.4.6
copy string a to string b and change string b with toupper() and count the chars
View 3 Replies View RelatedI am using gtk to program GUI. How can I show the output of shell command into a textbox, ex ps -efc command ?
View 3 Replies View RelatedI used a command Code:
grep -r err_sys ./
its output is
Code:
./tcpclitime.c:err_sys("socket error");
./tcpclitime.c:err_sys("connect error");
./tcpclitime.c:err_sys("write error");
./tcpclitime.c:err_sys("shutdown error");
./tcpclitime.c:err_sys("read error, n = %d", n);
[Code].....
Is it possible some how to replace all the occurrences of word err_sys by printf.
I am web developer I have this command find . -exec grep "Improve your score" '{}' ; -print for searching through files . I found this command but now i would like to tweak it to gain more out of it.
View 2 Replies View RelatedMy script.
This is may script:
Code:
Problem: Output file doest not exclude the values in grep -av
I wanted to find and replace a string from a perl file. I have written a script in bash which runs the following command.
perl -pi -e "s/$findstring/$replacestring/" testfile
where as $findstring = print F_WC_TMP"$line
";
and $replaceString = $line = join ' ', split ' ', $line; print F_WC_TMP"$line
";
But when I am running the above command, i think it is replacing the $findstring with the above mentioned string and hence it contains a $line, it is looking for the variable $line and not finding the exact string. I am confused about how to search for a string that contains $ in it and replace it with another $string.
The output of a command changed and I need to extract the data and print it out in a different fassion:
Code:
abcd1=aaaa xx
abcd 2 aaa xx bbb
abcd2=aaaa xy
ab 2 xx aaa bbb ccc xxx
should be transformed to:
[Code]...
Currently I used sed "search1|search2|search3" to get the lines that need to be transformed. But I also need to search for substrings in those lines and I need to print those substrings in a specific order together with other characters. How is this done with sed?
I am trying to grep multiple numbers from file, grep does have the -f option for that.
Code: grep -f <`seq 500 520` /etc/passwd I know this could be done with
Code: for i in `seq 500 520`; do grep "$i" /etc/passwd; done But my question is fare more behind this example. It is possible to redirect one command output which will be treat as a content of file for another command ?
I try to write script and echo two command at the same line .
echo "A"
echo "B"
How can I pipe above two command at the same line in text file . So, in the output text file , you can see below ? Code: A B not Code: A B
I'm troubleshooting a batch of scripts I'm modifying, including an IDL script called by a .csh script. the IDL scripts were provided to me by a coworker and my .csh script is intended to automate a lengthy set of extremely tedious and time consuming processing tasks.
I am currently in the process of debugging, and can't get the IDL to print any messages other than critical failures to the screen. Is there any easy way to redirect the stdout to either a logfile or the screen?
While making a shell ,there is the following problem Im facing:
I am expecting the user to enter commands in the following format :
I am to separate these and the output of ls -l should be given as input to grep and the output of both to more.
But I am allowed (by our instructor) to use dup/dup2 or any other command(but not pipe or tees).
How to connect the file descriptors after successful execution of each command?
I need to find one RUNNING word in latest created logs.
and as soon as i will get RUNNING WORD , i have to execute another Unix Command.
I wrote following script code...
After typing "man cut" in my terminal I can't seem to find this answer.
I am trying to write several shell scripts and want to remove the 'lp:<package name>' from the beginning of each line of the output of "bzr ls" as well as any notices at the beginning of the output, leaving only file and folder paths.
I am trying to process a column separated data file, with a few bash command. For example, I have
Code:
file1 aaaa yes
file2 aaaa no
file3 bbbb yes
Let say I want to create new file with the output of first column and do something else with the output of 3rd column. Of course there are many ways to process this data file, but I wish to know by using awk, how could I do it. I'm trying:
Code:
awk '{system("touch $1")}' datafile
but the shell command will not able to get the awk '$1' output. How do I get this done ? And for another question, if the data file contains the variable name of a shell variable, how could I make use of it during a awk output ? For example I have a datafile1:
Code:
server1 yes
server2 no
And in another server declaration data file, I got this datafile2:
Code:
server1=xxx1
server2=yyy1
And in my awk script, I want to achieve something like (the syntax is definitely wrong, just to demonstrate what I assume it will like):
[code]....
I am trying to execute a Unix Command in perl and assigning its output to an array:
Code:
@File_List=exec("ls -1 /tmp");
but it is not working. I have tried the perl function system() also but its return code is
[code]...
Suppose I want to account number of files beginning with abc , I can use "ls 'abc* | grep abc | wc -l", this will return me a number.
I want to store this number in a variable, say var1, so I tried
1. "ls 'abc* | grep abc | wc -l |read var1", but this didn't work as var1 has no value somehow.
2. var1='ls 'abc* | grep abc | wc -l', this just assign the entire string "ls 'abc* | grep abc | wc -l" to var1, which is not I wanted.
I don't want to store the value to a temporary file and then read the value from that file. I think there should be a direct way to get the value, but don't know how. I know in tcsh, one can just use set var1='ls 'abc* | grep abc | wc -l', but it also doesn't work in bash. Can anyone give any clue about this?
I'm trying to pull out sections from a bunch of files. For one file, I use:
Code:
sed '/string1/,/string2/ !d' <filename.ext >newfilename.ext
to pull out everything between two strings in the original file and put them in a new file.
[code]....
Is it possible to organize bash script output of which is like on top command i.e. monitoring every let's say 1 sec and old information would cleared?
View 3 Replies View RelatedI was messing around with Bash scripting just now and was wondering if there was a way to organize the output of a command into an array. Like the Bash equivalent of the PHP explode() function.
View 3 Replies View RelatedHere is what I am doing I have a file, a.txt for example, with following contents:
Code:
coreutils install
cpio install
cpp install
cpp-4.3 install
dbus install
[Code]...
So it seems like the sorting algo. for dpkg --get-selections is different than sorting algo. of 'sort' command when it encounters "-" (hyphen). How can I sort the original file (a.txt) in such a way that it produces the output file ,b.txt, exactly the same.
I have a command which generates the following output:
Code:
$ sudo vnconfig -l
vnd0: not in use
[code]...
The output of my fdisk command is as follows :-zodiac@gml-admin:~$ sudo fdisk -l[sudo] password for zodiac: Disk /dev/sda: 160.0 GB, 160041885696 bytes255 heads, 63sectors/track, 19457 cylindersUnits = cylinders of 16065 * 512 = 8225280 bytesSector size (logical/physical): 512 bytes / 512 bytesI/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0xe30ce30c
Device Boot Start End Blocks Id System
/dev/sda1 * 1 1958 15727603+ 7 HPFS/NTFS
/dev/sda2 1959 4752 22437838 f W95 Ext'd (LBA)
[code]...
I have a command that outputs n lines of text, and I want to place each line into an array element, but I can't seem to get the syntax correct
So my command is this:
cat $configfile | sed -n '/cluster:'$clustername'/,/cluster/ p' | awk /host/
Which produces many lines depending on the value of $clustername. I'd like to get each line as elements of an array.
I have a set of lines as ahown below:
Leon went to school
Leon came back from school..
Leon had dinner...
I have to replace the line containing "dinner" by a single string LUNCH...
I need to creates string suffixes out of a Reference string. for eg. suffixes of abcdefg will be
1)bcdefg
2)cdefg
3)defg
and so on...
create an array of pointers to point to the first few characters and then use that pointer to print the rest of the string.But when i print using the pointer i get GARBAGE values! shudn't std::cout<<ptr[w] print the string following the char it is pointing to? why do i get garbage values?
So if I'm given a location of a file like:
How can I just take the type of the file at the end? I know I can use strrchr() for a period to get the pointer to the period just before file type. Is there a build in string function that will just take the rest of the string from a certain point on forward in the string? I know it wouldn't be much work to make it myself, but I figured I would find out if it already existed before doing it.