Linux Notes: GnuCOBOL on Linux

1. The information presented here is intended for educational use by qualified computer technologists.
2. The information presented here is provided free of charge, as-is, with no warranty of any kind.

back to: Linux Notes (index)
Edit: 2026-10-03

Introduction

Back in the days of mainframes and minicomputers, COBOL licenses were very expensive (eg. starting at tens of thousands of dollars per machine).

One neat thing about Linux and open source software is that a fairly good COBOL compiler called GnuCOBOL could be downloaded then installed for zero dollars.

The following instructions describe nothing new and are only meant to pique your curiosity.

Installing GnuCOBOL (on RHEL, CentOS, AlmaLinux, etc)

caveats:

• this product goes by two names. You will be installing gnucobol but will invoking (or getting manual help about) cobc which sometimes is referred to as cobol-c  
• yum is the package manager on EL7 distros like CentOS-7 and RHEL-7. Starting with EL8, yum commands are translated into dnf commands (this change was made so that older installation and maintenance scripts would continue to work properly)
• yum (or dnf) must either be run buy root, or must be prepended with sudo

online help: https://gnucobol.sourceforge.io/doc/gnucobol.html

A few very important compiler switches (of many)

hello-world

hello-world-classic.cob

Notes:

• Recall that classic COBOL remarks begin in column-7 while code begins in column-8.
• Also, code must not extend beyond column 72
• These rules come from the days of punched cards which preceded interactive video terminals.
• The code:

        *  1         2         3         4         5         6
        *89012345678901234567890123456789012345678901234567890
        * file   : hello-world-classic.cob
        * notes  : this is a classic COBOL demo
        * build  : cobc -x hello-world-classic.cob
        * execute: ./hello-world-classic
        * history:
        * when       who what
        * 2023-02-14 NSR original effort
         IDENTIFICATION DIVISION.
         PROGRAM-ID. hello-world-classic.
         PROCEDURE DIVISION.
         DISPLAY "Hello World!".
         STOP RUN.
  

• Test run:

  $ cobc -x hello-world-classic.cob
  $ ./hello-world-classic
  Hello World!
  $ 

hello-world-free-format.cob

Notes:

• Compiling with the "-free" switch removes all indenting requirements, and moves the right column restriction from 72 to 511.
• The only hard rule is this: all classic COBOL remarks (eg. lines that begin with an asterisk) must be changed from "*"  to "*>"
• Here, I retained left-margin indenting so that syntax coloring still works when editing via vim. But this program would compile properly if you removed all the left-side white-space.
• The code:

        *> file   : hello-world-free-format.cob
        *> notes  : this is a free format COBOL demo
        *> build  : cobc -x -free hello-world-free-format.cob
        *> execute: ./hello-world-free-format
        *> history:
        *> when       who what
        *> 2023-02-14 NSR original effort
         IDENTIFICATION DIVISION.
         PROGRAM-ID. hello-world-classic.
         PROCEDURE DIVISION.
         DISPLAY "Hello World!".
         STOP RUN.
  

• Test run:

  $ cobc -x -free hello-world-free-format.cob
  $ ./hello-world-free-format
  Hello World!
  $

indexed-file support via ISAM

a few words about ISAM

• ISAM was all the rage from 1965 to 1990 on mainframes and minicomputers. SQL replaced ISAM in most applications after 1990.
  
  • ISAM = Indexed Sequential Access Method (predates an SQL-compliant relational database).
  • Recall that ISAM support was built into both DEC-BASIC and DEC-COBOL on VMS and OpenVMS.
    • It could be called (so implemented with a little more difficulty) by other DEC languages including Pascal and C.
  • Unlike traditional mainframe operating systems, modern environments (like Linux, Windows, or macOS) do not have native, record-oriented system services built-in. To handle COBOL's Indexed Sequential Access Method (ISAM) files (ORGANIZATION IS INDEXED), cobc relies on an external software library. By default, GnuCOBOL is configured to use Berkeley DB to manage these keys and records.

    $ cobc --info | grep -i index
      indexed file handler     : BDB
    

  • You must rebuild the compiler if you wish to switch indexing support from BDB to one of: VBISAM, C-ISAM, or DIASM
  • Inspect the program below then notice that the record is defined using a group of PIC statements (In DEC-BASIC you would declare a MAP containing fixed-length strings)
    • PIC 9 = numeric [[[ so PIC 9(4) reserves space for 4 numbers ]]]
    • PIC X = alphanumeric [[[ so PIC X(20) reserves space for 20 alpha-numeric characters ]]]
    • PIC A = alphabetic [[[ so PIC A(10) reserves space for 10 alphabetic characters) ]]]
  • Notice that PIC statements are also used to define working storage (program variables)

indexed-file-demo1.cob

Notes:

• The following example was recently sent by a peer following one of our discussions about ISAM
  • Apparently this demo was auto-created by Google's Gemini A.I. in 2026
  • It does not compile "as-is" using GnuCOBOL because one of the lines (109 in this file) is longer than 72 characters.
  • Since the format of line 109 is different than 126, I would say that the A.I. must have FUBARed line 109.
  • Anyway, this can be easily compiled using GnuCOBOL with the inclusion of the "-ftext-column=132" switch
• The code:  index-file-demo1.cob

indexed-file-demo2.cob

Notes:

• The following example was translated from this DEC-BASIC demo ( rms_indexed_demo.bas ) to GnuCOBOL by Google Gemini in Sep-2026.
• I intended to do it myself then decided to try one of the new A.I. utilities.
• The translation contained 303 compiler-time errors:
  • many vanished after I used VIM to replace "*" with "*>" then recompiled using the "-free" switch
  • one syntax error was associated with COB_DELETE_FILE so I rewrote that section.
• The code: index-file-demo2.cob

Index of local demo programs

Gotchas, FUBARs, and SNAFUs

Number 1 (DISPLAY WITH NO ADVANCING)

• despite what you may have read online, DISPLAY WITH NO ADVANCING will usually work with most COBOL implementations, including GnuCOBOL, provided you do not modify CONSOLE
• The following program will not compile until you remove the line "CONSOLE IS CRT"
• The code:

        *> ==========================================================
        *> title  : display-gotcha.cob
        *> author : Neil Rieck
        *> created: 2026-09-30
        *> compile: cobc -x -free display-gotcha.cob
        *> notes  :
        *> 1) changing CONSOLE breaks DISPLAY WITH NO ADVANCING so
        *>    this program will not compile as-is.
        *> 2) To fix this program you must remove "CONSOLE IS CRT."
        *> ==========================================================
         IDENTIFICATION DIVISION.
         PROGRAM-ID. display-gotcha.
         AUTHOR. Neil Rieck.
         ENVIRONMENT DIVISION.
         CONFIGURATION SECTION.
         SPECIAL-NAMES.
             CONSOLE IS CRT.
         DATA DIVISION.
         WORKING-STORAGE SECTION.
         01  WS-CONTROL-VARS.
             05  JUNK-INPUT          PIC X(10) VALUE SPACES.
             05  JUNK-CHAR           PIC X(1)  VALUE SPACES.
  
         PROCEDURE DIVISION.
         MAIN-PROGRAM.
             DISPLAY "display-gotcha"
             DISPLAY "Continue? (y/N) " WITH NO ADVANCING
             ACCEPT JUNK-INPUT
             PERFORM EXTRACT-FIRST-UPPER
             IF JUNK-CHAR = "Y"
                 DISPLAY "continuing"
             ELSE
                 DISPLAY "not continuing"
             END-IF
             GO TO PROGRAM-EXIT.
  
         EXTRACT-FIRST-UPPER.
             MOVE FUNCTION UPPER-CASE(FUNCTION TRIM(JUNK-INPUT))
                 TO JUNK-INPUT
             IF JUNK-INPUT = SPACES
                 MOVE "N" TO JUNK-CHAR
             ELSE
                 MOVE JUNK-INPUT(1:1) TO JUNK-CHAR
             END-IF.
  
         PROGRAM-EXIT.
             DISPLAY "Adios..."
             STOP RUN.

• Failed Build:

  $ cobc -x -free display-gotcha.cob
  display-gotcha.cob: in paragraph 'MAIN-PROGRAM':
  display-gotcha.cob:28: error: cannot specify NO ADVANCING in screen DISPLAY
     26 |            DISPLAY "Display-FUBAR"
     27 |            DISPLAY "Continue? (y/N) " WITH NO ADVANCING
     28 >            ACCEPT JUNK-INPUT
     29 |            PERFORM EXTRACT-FIRST-UPPER
     30 |            IF JUNK-CHAR = "Y"
  $

Number 2 (program compiles but will not run)

• On some Linux systems, shared libraries installed by you do not (by default) have their bindings loaded into memory.
• This means that some dynamically linked programs will not run.
• You can fix this by requesting that cobc perform a static link (this demo uses mariadb; your program might be using mysql)

  $ # attempt 1
  $ cobc -x -free               mysql-demo-native.cob -lmariadb
  $ ./mysql-demo-native
  MySQL-Demo-Native
  =================
  OK to delete 'demo data table'? (y/N)y
  libcob: error: module 'mysql_init' not found
  $ # attempt 2
  $ cobc -x -free -fstatic-call mysql-demo-native.cob -lmariadb
  $ ./mysql-demo-native
  MySQL-Demo-Native
  =================
  OK to delete 'demo data table'? (y/N)y
  -e- error:      1045 in connect
  -i- text : Access denied for user 'demo'@'localhost' (using password: YES)
  Adios...
  $

  or by commanding your system to load the library bindings (this demo uses mariadb; your program might be using mysql)

  $ # get help
  $ ldconfig -?
  $       ....verbage ensues...
  $ # is library installed in memory?
  $ ldconfig -p | grep -i mariadb
  $ # install all libraries
  $ ldconfig
          ...verbage ensues...
  $ # is library installed in memory?
  $ ldconfig -p | grep -i mariadb
          libmariadb.so.3 (libc6,x86-64) => /lib64/libmariadb.so.3
          libmariadb.so (libc6,x86-64) => /lib64/libmariadb.so
  $
  

Links

• Internal to this site:
  • back to: Linux Notes (index)
  • gcc-32-bit-compile-on-64-bit-rhel
  • See an ISAM example program written in DEC-BASIC on VMS and OpenVMS
• External
  • https://gnucobol.sourceforge.io/
  • https://gnucobol.sourceforge.io/guides.html
  • https://gnucobol.sourceforge.io/doc/gnucobol.html
  • https://cobolworx.com/
  • https://www.vajhoej.dk/arne/articles/vmstd6.html - converting between VMS COBOL and GnuCOBOL

---

Back to Home
Neil Rieck
Waterloo, Ontario, Canada.