04-26-2006
how could i make a program mixed with many "|", "<" and ">"
I have written following code to do: ls -l | wc -w, it works:
but when there are not only a single "|", if there are more such as:
ls -l | sort -r | sort | sort -r, This program does not work, i want to know how could i deal with it when there are more "|", another situation is that, if it mixes "|" and "<" or ">", such as: cat < apa | wc | wc >h***, this is also complex, how could i deal with these? thank you very much
(The following is just for a single "|")
void pipeProcess(char *args1[], char *args2[]) {
int thepipe[2], pid;
if(pipe(thepipe) == -1)
oops("Can not get a pipe", 1);
/* Create a new process */
if((pid = fork()) == -1)
oops("Can not fork", 2);
if(pid >0) {/* This is parent process */
close(thepipe[1]); /* parent does not write to pipe */
if(dup2(thepipe[0], 0) == -1) /* let parent read interface attaches to stdin */
oops("Could not redirect stdin", 3);
close(thepipe[0]); /* close thepipe[0] interface because it has attached to stdin */
execvp(args2[0], args2);
oops(*args2, 4);
}
/* Child process executes av[1] and writesinto pipe */
close(thepipe[0]); /* Child does not read from pipe */
if(dup2(thepipe[1], 1) == -1)
oops("Could not redirect stdout", 4);
close(thepipe[1]);
execvp(args1[0], args1);
oops(*args1, 5);
}
9 More Discussions You Might Find Interesting
1. UNIX for Dummies Questions & Answers
Hi Friends,
Can any of you explain me about the below line of code?
mn_code=`env|grep "..mn"|awk -F"=" '{print $2}'`
Im not able to understand, what exactly it is doing :confused:
Any help would be useful for me.
Lokesha (4 Replies)
Discussion started by: Lokesha
4 Replies
2. Shell Programming and Scripting
hi All,
cat file_name | awk /^~/'{print $1","$2","$3","$4}' | sed -e 's/~//g'
Can this be done by using sed or awk alone (4 Replies)
Discussion started by: harshakusam
4 Replies
3. Shell Programming and Scripting
This is the script:
#!/bin/sh
if ; then rm -rf /usr/share/WallpaperChanger; fi
if ; then rm -rf /usr/bin/wallch; fi;
if ; then rm -rf /usr/share/applications/wallch.desktop; fi
if ; then rm -rf /usr/share/doc/wallch; fi
if ; then rm -rf /usr/share/man/man1/wallch.1.gz; fi
echo "Delete... (4 Replies)
Discussion started by: hakermania
4 Replies
4. Shell Programming and Scripting
Hi,
I have line in input file as below:
3G_CENTRAL;INDONESIA_(M)_TELKOMSEL;SPECIAL_WORLD_GRP_7_FA_2_TELKOMSEL
My expected output for line in the file must be :
"1-Radon1-cMOC_deg"|"LDIndex"|"3G_CENTRAL|INDONESIA_(M)_TELKOMSEL"|LAST|"SPECIAL_WORLD_GRP_7_FA_2_TELKOMSEL"
Can someone... (7 Replies)
Discussion started by: shis100
7 Replies
5. Shell Programming and Scripting
logs:
"/home/abc/public_html/index.php"
"/home/abc/public_html/index.php"
"/home/xyz/public_html/index.php"
"/home/xyz/public_html/index.php"
"/home/xyz/public_html/index.php"
how to use "cut" or "awk" or "sed" to get the following result:
abc
abc
xyz
xyz
xyz (8 Replies)
Discussion started by: timmywong
8 Replies
6. Solaris
The system don't boot.
on the screen appears following:
press enter to maintenance (or type CTRL-D to continue)...I checked with format command.
... the slices "0-root","1-swap","2-backup" exist.
...the slises "3-var","6-usr" -unassigned. :( (16 Replies)
Discussion started by: wolfgang
16 Replies
7. UNIX for Dummies Questions & Answers
How to use "mailx" command to do e-mail reading the input file containing email address, where column 1 has name and column 2 containing “To” e-mail address
and column 3 contains “cc” e-mail address to include with same email.
Sample input file, email.txt
Below is an sample code where... (2 Replies)
Discussion started by: asjaiswal
2 Replies
8. Shell Programming and Scripting
Hello.
System : opensuse leap 42.3
I have a bash script that build a text file.
I would like the last command doing :
print_cmd -o page-left=43 -o page-right=22 -o page-top=28 -o page-bottom=43 -o font=LatinModernMono12:regular:9 some_file.txt
where :
print_cmd ::= some printing... (1 Reply)
Discussion started by: jcdole
1 Replies
9. AIX
Hi 2 all,
i have had AIX 7.2
:/# /usr/IBMAHS/bin/apachectl -v
Server version: Apache/2.4.12 (Unix)
Server built: May 25 2015 04:58:27
:/#:/# /usr/IBMAHS/bin/apachectl -M
Loaded Modules:
core_module (static)
so_module (static)
http_module (static)
mpm_worker_module (static)
... (3 Replies)
Discussion started by: penchev
3 Replies
LEARN ABOUT DEBIAN
filter_create_fd
filter_create_fd(3) util/filter.h filter_create_fd(3)
NAME
filter_create_fd - Create a sub process and return the requested pipes
SYNOPSIS
#include <util/filter.h>
NEOERR *filter_create_fd(const char *cmd, int *fdin, int *fdout, int *fderr,
pid_t *pid);
ARGUMENTS
cmd -> the sub command to execute. Will be executed with
/bin/sh -c
fdin -> pointer to return the stdin pipe, or NULL if you don't
want the stdin pipe
fdout -> pointer to return the stdout pipe, or NULL if you don't
want the stdout pipe
fderr -> pointer to return the stderr pipe, or NULL if you don't
want the stderr pipe
DESCRIPTION
filter_create_fd and filter_create_fp are what popen
been: a mechanism to create sub processes and have pipes to all their input/output. The concept was taken from mutt, though python has
something similar with popen3/popen4. You control which pipes the function returns by the fdin/fdout/fderr arguments. A NULL value means
"don't create a pipe", a pointer to an int will cause the pipes to be created and the value of the file descriptor stored in the int. You
will have to close(2) the file descriptors yourself.
RETURN VALUE
fdin -> the stdin file descriptor of the sub process
fdout -> the stdout file descriptor of the sub process
fderr -> the stderr file descriptor of the sub process
pid -> the pid of the sub process
SEE ALSO
filter_wait(3), filter_create_fp(3), filter_create_fd
ClearSilver 12 July 2007 filter_create_fd(3)