C Library Functions - regsub (3)
NAME
regsub(3f) - [M_regex] perform regex substitutions
CONTENTS
Synopsis
Description
Options
Examples
SYNOPSIS
subroutine regsub(matchline, matches, source, dest)
character(len=*),intent(in) :: matchline integer,intent(in) :: matches(:,:) character(len=*),intent(in) :: source character(len=:),allocatable,intent(out) :: dest
DESCRIPTION
The regsub() function copies source to dest, making substitutions according to the most recent regexec() performed using MATCHES(:,:).Each instance of "&" in source is replaced by the substring indicated by the start and end array MATCHES(:,:).
Each instance of "\n", where n is a digit, is replaced by the substring indicated by MATCHES(1,n) and MATCHES(2,n).
To get a literal "&" or "\n" into dest, prefix it with "\"; to get a literal "\" preceding "&" or "\n", prefix it with another "\".
OPTIONS
MATCHLINE line REGEXEC(3f) was run against MATCHES output array from REGEXEC(3f) call SOURCE output template string containing "&" and/or "\n" indicating where to make substitutions DEST output string
EXAMPLES
Sample program that reads an array of lines representing a Unix /etc/passwd file and uses an RE (Regular Expression) to read fields from the line and then uses REGSUB(3f) to print strings using the matched strings
program demo_regsub use M_regex, only: regex_type, regcomp, regexec, regerror, regmatch, regfree, regsub implicit none type(regex_type) :: regex integer,parameter :: maxmatch=10 integer :: matches(2,maxmatch) character(len=:),allocatable :: input_line(:) character(len=:),allocatable :: output_line character(len=:),allocatable :: expression logical :: match integer :: stat integer :: i logical :: BRE ! The /etc/passwd file is a colon-separated file that contains the following information: ! ! User name. ! Encrypted password. ! User ID number (UID) ! User’s group ID number (GID) ! Full name of the user (GECOS) ! User home directory. ! Login shell. ! BRE=.true. if(BRE)then ! BRE (Basic Regular Expression) expression= ’\([^:]*\):*\([^:]*\):*\([^:]*\):*\([^:]*\):*\([^:]*\):*\([^:]*\):*\([^:]*\):*.*’ call regcomp(regex,expression,status=stat) else ! ERE (Extended Regular Expression) expression= ’([^:]*):*([^:]*):*([^:]*):*([^:]*):*([^:]*):*([^:]*):*([^:]*):*.*’ call regcomp(regex,expression,’x’,status=stat) endifif(stat.ne.0)then ! if RE did not compile report error write(*,*)’*regcomp* ERROR:’,regerror(regex,stat) stop 1 endif
! simulate /etc/password file in array, with common aberrant input lines included input_line= [character(len=128) :: & "doeqj:xxxxx:1001:200:John Q. Doe:/home/doeqj:/bin/tcsh: and more", & "doeqj:xxxxx:1001:200:John Q. Doe:/home/doeqj:/bin/tcsh: and more:", & "doeqj: :1001: :John Q. Doe:/home/doeqj:/bin/tcsh:", & "doeqj:xxxxx:1001:200:John Q. Doe:/home/doeqj:/bin/tcsh:", & "doeqj:xxxxx:1001:200:John Q. Doe:/home/doeqj:/bin/tcsh", & "doeqj:xxxxx:1001:200:John Q. Doe:/home/doeqj", & "doeqj:xxxxx:", & "doeqj:xxxxx", & "doeqj:", & "doeqj", & ! the RE shown needs the field to have at least one character ! which should be replaced first, but not shown in this example ": : : : : : : : : : : : : : :", & ": ::", & "" ]
do i=1,size(input_line) match=regexec(regex,input_line(i),matches) ! generate the matches array using the compiled RE
write(*,’(a)’)repeat(’-’,80) ! put out a number line write(*,’(a)’) input_line(i) ! replace \n lines call regsub(input_line(i),matches,’username="\1" & &password="\2" UID="\3" GID="\4" name="\5" & &home="\6" shell="\7" ’,output_line) write(*,’(a)’) output_line
if(i.eq.1)then ! show other examples of formatting for first entry call regsub(input_line(i),matches,& & ’The username for \5 is "\1"’,output_line) write(*,’(a)’) output_line
call regsub(input_line(i),matches,& & ’username "\1" has UID=\3, GID=\4 & & and default shell "\7"’,output_line) write(*,’(a)’) output_line endif enddo
call regfree(regex)
end program demo_regsub -------------------------------------------------------------------------------- doeqj:xxxxx:1001:200:John Q. Doe:/home/doeqj:/bin/tcsh: and more username="doeqj" password="xxxxx" UID="1001" GID="200" name="John Q. Doe" home="/home/doeqj" shell="/bin/tcsh" The username for John Q. Doe is "doeqj" username "doeqj" has UID=1001, GID=200 and default shell "/bin/tcsh" -------------------------------------------------------------------------------- doeqj:xxxxx:1001:200:John Q. Doe:/home/doeqj:/bin/tcsh: and more: username="doeqj" password="xxxxx" UID="1001" GID="200" name="John Q. Doe" home="/home/doeqj" shell="/bin/tcsh" -------------------------------------------------------------------------------- doeqj: :1001: :John Q. Doe:/home/doeqj:/bin/tcsh: username="doeqj" password=" " UID="1001" GID=" " name="John Q. Doe" home="/home/doeqj" shell="/bin/tcsh" -------------------------------------------------------------------------------- doeqj:xxxxx:1001:200:John Q. Doe:/home/doeqj:/bin/tcsh: username="doeqj" password="xxxxx" UID="1001" GID="200" name="John Q. Doe" home="/home/doeqj" shell="/bin/tcsh" -------------------------------------------------------------------------------- doeqj:xxxxx:1001:200:John Q. Doe:/home/doeqj:/bin/tcsh username="doeqj" password="xxxxx" UID="1001" GID="200" name="John Q. Doe" home="/home/doeqj" shell="/bin/tcsh" -------------------------------------------------------------------------------- doeqj:xxxxx:1001:200:John Q. Doe:/home/doeqj username="doeqj" password="xxxxx" UID="1001" GID="200" name="John Q. Doe" home="/home/doeqj" shell="" -------------------------------------------------------------------------------- doeqj:xxxxx: username="doeqj" password="xxxxx" UID="" GID="" name="" home="" shell="" -------------------------------------------------------------------------------- doeqj:xxxxx username="doeqj" password="xxxxx" UID="" GID="" name="" home="" shell="" -------------------------------------------------------------------------------- doeqj: username="doeqj" password="" UID="" GID="" name="" home="" shell="" -------------------------------------------------------------------------------- doeqj username="doeqj" password="" UID="" GID="" name="" home="" shell="" -------------------------------------------------------------------------------- : :: :: :: :: :: :: :: username="" password=" " UID=" " GID=" " name=" " home=" " shell=" " -------------------------------------------------------------------------------- : :: username="" password=" " UID="" GID="" name="" home="" shell="" --------------------------------------------------------------------------------
username="" password="" UID="" GID="" name="" home="" shell=""
| Nemo Release 3.1 | regsub (3) | February 23, 2025 |
