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Full Discussion: Statement to find if an entry exists in a file
Top Forums UNIX for Dummies Questions & Answers Statement to find if an entry exists in a file Post 302638047 by neutronscott on Wednesday 9th of May 2012 09:09:33 PM
Old 05-09-2012
What OS version and which shell? You can also try awk to replace grep.

Code:
record_file=/path/to/some/file.txt

record_exists() {
    awk -v "record=$1" 'index($0,record) {found=1;exit} END {exit !found}' "$record_file"
}

read record
if record_exists "$record"; then
  #do stuff
else
  #do other stuff
fi

edit: to be more specific about matching, if your record file is for instance delimited you can check a specific field. for instance finding a username in /etc/passwd. /etc/passwd is delimited with : and the username is the first field

Code:
user_exists() {
    awk -F: -v "user=$1" '$1 == user {found=1;exit} END {exit !found}' /etc/passwd
}

Last edited by neutronscott; 05-09-2012 at 10:15 PM..
 

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LEARN ABOUT ULTRIX

shexp

shexp(1)						      General Commands Manual							  shexp(1)

Name
       shexp - display password expiration information for a user

Syntax
       shexp [-q] [username]

Description
       The command is used to display a user's password expiration information.  The specified username, or logname if no username is supplied, is
       converted to a UID by searching through the passwd file.  The UID is then used to look up the user's entry in  the  Auth  Data  Base.   The
       password expiration information is then printed out in format.
       % shexp
       Expires Tue Dec	6 10:49:18 EST 1988
       If  the	password  has  already expired the word Expires will be replaced with the word Expired. If password expiration is disabled for the
       particular user in question the output of will be Never expires.

Options
       -q   Instead of displaying the expiration date and time in format, outputs it as three decimal numbers: the minimum password lifetime,  the
	    maximum password lifetime, and the password modification time.  All three numbers are displayed as they are found in the database.

Restrictions
       Only the super-user may obtain information about users with UIDs other than the real UID of the invoking process.

Diagnostics
       User not found in passwd data base.
       There is no entry in for the specified username.

       Cannot stat auth file.
       The database is missing (security features may not be enabled).

       Insufficient privilege.
       An insufficiently privileged user is asking for information about a username with a UID different then their current real-UID.

       An exit value of 0 indicates a successful operation, any other exit status indicates an error.

Files
See Also
       passwd(1), getauthuid(3), auth(5)
       Security Guide for Users

																	  shexp(1)
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