What am I doing wrong here? Post: 302524268

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Top Forums UNIX for Advanced & Expert Users What am I doing wrong here? Post 302524268 by methyl on Sunday 22nd of May 2011 08:36:59 PM

05-22-2011

Registered User

One idea is to count the number of times a user appears in the "who -u" list by using the "wc -l" command (which just counts the number of lines it sees).
The backticks ` ` are important and cause the commands to be executed. Note the correct syntax for an "if" statement. Not clear where the "do" and "done" figure in Post #1.

Code:

#!/bin/sh
echo "please enter a user name"
read user
user_login_count=`who -u | grep "^${user} " | wc -l`
if [ ${user_login_count} -gt 0 ]
then
       echo "User ${user} is logged in ${user_login_count} times"
       # Show some evidence
       who -u | grep "^${user} " | awk '{print $1}'
else
       echo "User ${user} is not logged in"
fi

If you have a modern POSIX shell, the line containing the backticks can be replaced with the more eloquent:

Code:

user_login_count=$(who -u | grep "^${user} " | wc -l)

When posting it always helps to say what Operating System and Shell you have. There is much variation.

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LEARN ABOUT LINUX

zegrep

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)

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