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UNIX for Advanced & Expert Users
URGENT Help required regarding the use of FORK system call
Post 8123 by rwb1959 on Friday 5th of October 2001 05:15:12 PM
10-05-2001
The previous guru's are quite correct.
I might even suggest that you forget about fork(), wait(),
SIGCHLD, etc. and just launch 5 different instances of the
same program with say a file name as an argument...
#!/bin/ksh
myprog file1 > /tmp/file1.$$ &
kid1pid=$!
myprog file2 > /tmp/file2.$$ &
kid2pid=$!
....
myprog file5 > /tmp/file3.$$ &
kid5pid=$!
# at this point you wait on the kids
wait
# here you can assemble the files...
Cwd=`pwd`
cd /tmp
for i in `ls file?.*`
do
cat $i >> $Cwd/newfile.$$
done
rm -f file?.*
cd $Cwd
exit 0
...so... it ain't pretty, it ain't slick or elegant, hell, it ain't even C
but it is simple and will work by Monday
I might even suggest that you forget about fork(), wait(),
SIGCHLD, etc. and just launch 5 different instances of the
same program with say a file name as an argument...
#!/bin/ksh
myprog file1 > /tmp/file1.$$ &
kid1pid=$!
myprog file2 > /tmp/file2.$$ &
kid2pid=$!
....
myprog file5 > /tmp/file3.$$ &
kid5pid=$!
# at this point you wait on the kids
wait
# here you can assemble the files...
Cwd=`pwd`
cd /tmp
for i in `ls file?.*`
do
cat $i >> $Cwd/newfile.$$
done
rm -f file?.*
cd $Cwd
exit 0
...so... it ain't pretty, it ain't slick or elegant, hell, it ain't even C
but it is simple and will work by Monday
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LEARN ABOUT OPENSOLARIS
comm
comm(1) User Commands comm(1) NAME
comm - select or reject lines common to two files SYNOPSIS
comm [-123] file1 file2 DESCRIPTION
The comm utility reads file1 and file2, which must be ordered in the current collating sequence, and produces three text columns as output: lines only in file1; lines only in file2; and lines in both files. If the input files were ordered according to the collating sequence of the current locale, the lines written will be in the collating sequence of the original lines. If not, the results are unspecified. OPTIONS
The following options are supported: -1 Suppresses the output column of lines unique to file1. -2 Suppresses the output column of lines unique to file2. -3 Suppresses the output column of lines duplicated in file1 and file2. OPERANDS
The following operands are supported: file1 A path name of the first file to be compared. If file1 is -, the standard input is used. file2 A path name of the second file to be compared. If file2 is -, the standard input is used. USAGE
See largefile(5) for the description of the behavior of comm when encountering files greater than or equal to 2 Gbyte ( 2^31 bytes). EXAMPLES
Example 1 Printing a list of utilities specified by files If file1, file2, and file3 each contain a sorted list of utilities, the command example% comm -23 file1 file2 | comm -23 - file3 prints a list of utilities in file1 not specified by either of the other files. The entry: example% comm -12 file1 file2 | comm -12 - file3 prints a list of utilities specified by all three files. And the entry: example% comm -12 file2 file3 | comm -23 -file1 prints a list of utilities specified by both file2 and file3, but not specified in file1. ENVIRONMENT VARIABLES
See environ(5) for descriptions of the following environment variables that affect the execution of comm: LANG, LC_ALL, LC_COLLATE, LC_CTYPE, LC_MESSAGES, and NLSPATH. EXIT STATUS
The following exit values are returned: 0 All input files were successfully output as specified. >0 An error occurred. ATTRIBUTES
See attributes(5) for descriptions of the following attributes: +-----------------------------+-----------------------------+ | ATTRIBUTE TYPE | ATTRIBUTE VALUE | +-----------------------------+-----------------------------+ |Availability |SUNWesu | +-----------------------------+-----------------------------+ |CSI |enabled | +-----------------------------+-----------------------------+ |Interface Stability |Standard | +-----------------------------+-----------------------------+ SEE ALSO
cmp(1), diff(1), sort(1), uniq(1), attributes(5), environ(5), largefile(5), standards(5) SunOS 5.11 3 Mar 2004 comm(1)