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Full Discussion: How to replace line through sed , but without uncommented?
Top Forums UNIX for Beginners Questions & Answers How to replace line through sed , but without uncommented? Post 303041840 by MadeInGermany on Thursday 5th of December 2019 03:03:20 AM
Old 12-05-2019
The second * in the previous post should be
Code:
sed 's/^\([[:space:]]*PASS_MIN_LEN[[:space:]]*\)[0-9][0-9]*/\112/' /etc/login.defs

Alternatively one can add a filter condition and use the s command:
Code:
sed -i '/^[^#]/ s/PASS_MIN_LEN.*/PASS_MIN_LEN 12/' /etc/login.defs

Or
Code:
sed -i '/^#/!s/PASS_MIN_LEN.*/PASS_MIN_LEN 12/' /etc/login.defs

Or branch to the end of the sed script if a comment is met; useful if several commands follow.
Code:
sed -i '
  /^#/b
  /PASS_MIN_LEN.*/c\PASS_MIN_LEN 12
' /etc/login.defs

Last edited by MadeInGermany; 12-05-2019 at 12:06 PM.. Reason: some corrections
 

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LEARN ABOUT LINUX

chfn

CHFN(1) 							   User Commands							   CHFN(1)

NAME

       chfn - change real user name and information

SYNOPSIS

       chfn [-f full_name] [-r room_no] [-w work_ph] [-h home_ph] [-o other] [user]

DESCRIPTION

       The chfn command changes user fullname, office number, office extension, and home phone number information for a user's account. This
       information is typically printed by finger(1) and similar programs. A normal user may only change the fields for her own account, subject
       to the restrictions in /etc/login.defs. (The default configuration is to prevent users from changing their fullname.) The superuser may
       change any field for any account. Additionally, only the superuser may use the -o option to change the undefined portions of the GECOS
       field.

       These fields must not contain any colons. Except for the other field, they should not contain any comma or equal sign. It is also
       recommended to avoid non-US-ASCII characters, but this is only enforced for the phone numbers. The other field is used to store accounting
       information used by other applications.

       If none of the options are selected, chfn operates in an interactive fashion, prompting the user with the current values for all of the
       fields. Enter the new value to change the field, or leave the line blank to use the current value. The current value is displayed between a
       pair of [ ] marks. Without options, chfn prompts for the current user account.

CONFIGURATION

       The following configuration variables in /etc/login.defs change the behavior of this tool:

       CHFN_RESTRICT (string)
	   This parameter specifies which values in the gecos field of the /etc/passwd file may be changed by regular users using the chfn
	   program. It can be any combination of letters f, r, w, h, for Full name, Room number, Work phone, and Home phone, respectively. For
	   backward compatibility, yes is equivalent to rwh and no is equivalent to frwh. If not specified, only the superuser can make any
	   changes. The most restrictive setting is better achieved by not installing chfn SUID.

FILES

       /etc/login.defs
	   Shadow password suite configuration.

       /etc/passwd
	   User account information.

SEE ALSO

       chsh(1), login.defs(5), passwd(5).

User Commands							    06/24/2011								   CHFN(1)
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