04-26-2002
Good example.
When you use a command like grep or find, they kick off subprocesses (children processes) that actually do the work.
EXAMPLE #1
The parent ( the command that you typed.) "find . -name somefile -print " kicks off subprocesses that actually go out and search for the file that you specified. When they are done they report back to the find command.
EXAMPLE #2
Using grep if you are trying to do something like matching a pattern(s) in a file to print out the lines.
cat filename|grep patterna
This command will actually spawn 2 processes. The cat command, the parent, and the grep command, the child. When the child (grep) finishes it returns to the parent (cat) with the result.
Example #3
Do a ps -aef |grep sh" to find your telnet session. Find your login and do a ps -aef |grep on that PID. All of your commands are technically children of your telnet session as you will see.
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ZGREP(1) General Commands Manual ZGREP(1)
NAME
zgrep - search possibly compressed files for a regular expression
SYNOPSIS
zgrep [ grep_options ] [ -e ] pattern filename...
DESCRIPTION
Zgrep invokes grep on compressed or gzipped files. These grep options will cause zgrep to terminate with an error code:
(-[drRzZ]|--di*|--exc*|--inc*|--rec*|--nu*). All other options specified are passed directly to grep. If no file is specified, then the
standard input is decompressed if necessary and fed to grep. Otherwise the given files are uncompressed if necessary and fed to grep.
If the GREP environment variable is set, zgrep uses it as the grep program to be invoked.
EXIT CODE
2 - An option that is not supported was specified.
AUTHOR
Charles Levert (charles@comm.polymtl.ca)
SEE ALSO
grep(1), gzexe(1), gzip(1), zdiff(1), zforce(1), zmore(1), znew(1)
ZGREP(1)