Shell Script Programming Challenge

I'm just trying give myself a test on problem solving skill using Bash programming.

Given a scenario where the file, say file_A, locate in directory dir_A is required to rename into this format pattern <file>_yyyymmdd.txt. I’m require to write a bash script to accomplish this task. In addition to this, dir_A sometimes may contain multiple files, the script must be able to handle such situation.

Here is my work:

...
...

for XFILE in `ls ${DIR_A} | grep -v "\."`
do
   mv ${XFILE} ${XFILE}_`date +%Y%m%d`.txt
done

Surprise me! It just take 4 lines of code.

Failed to transfer file with SFTP in batch mode

There is a problem when I transferring files over SFTP in batch mode. Say I have the file transfer script that do this:

sshpass –e sftp –b filelist.txt theuser@123.123.12.123:/home/theuser << EOF
bye
EOF

Assuming there is no problem found in filelist.txt, if the file transfer script is execute, the following error would be seen:

Permission denied (publickey,gssapi-keyex,gssapi-with-mic,password).
Couldn't read packet: Connection reset by peer

Running the sftp command with –v option shows that it seems not able to find the key pair for authentication. Later I found out that missing oBatchMode option may failed the process, thus this should be the work around I found in forum.

sshpass –e sftp –oBatchMode=no –b filelist.txt theuser@123.123.12.123:/home/theuser << EOF
bye
EOF

Passing authentication with SSHPASS

There is a requirement to create a cron script that will transfer files through SFTP command. But one problem I’m facing here is the script will prompt for password in order to proceed its job. This is not a correct behavior since a cron must be able to perform the task without human interaction.

Since the server is not yet ready for me to play around with, and I don’t know how to setup public/private key pair, the only way I can opt for is SSHPASS command. I think this should be the cheapest solution I could opt for. I do understand that SSHPASS is insecure and not encourage to use, but this should be fine under development stage.

Assuming I’m going to transfer a file to a destiny location at /home/theuser with username theuser and IP 123.123.12.123. With SFTP, this is what I’ll do in the script:

sftp theuser@123.123.12.123:/home/theuser << EOF
put thefile.txt
bye
EOF

Whenever this script is run, I’ll get a prompt for password then only the process will continue. Now if I do it with SSHPASS command, this is how it look like:

sshpass –p ‘password’ sftp theuser@123.123.12.123:/home/theuser << EOF
put thefile.txt
bye
EOF

There is also an alternate solution as shown below, by keeping the password in environment variable but which is strongly not a good way to go.

export SSHPASS=password
sshpass –e sftp theuser@123.123.12.123:/home/theuser << EOF
put thefile.txt
bye
EOF

Compiling C code with Informix 4GL

When I was assigned a task that involve integration work between MQ and 4GL, this was really exciting me because this will involve C programming language since C is my favorite language. But one thing to note is that this is not the regular C I’ve been doing in the pass. It is highly dependent on the version of Informix version I’m currently running.

As I ask around, the Informix environment we are running is called Rapid Development System, RDS for short. In this enviroment, there is a program that used to make the C code, named cfglgo.v2. It is not a compiler, rather it is a P-code (pseudocode) runner. My senior told me that there are also c4gl or i4gl, but these are not usable in ours environment. Following is the example on how this runner is call:

cfglgo.v2 -I/opt/mqm/inc fgiusr.c myrunner.c /opt/mqm/lib64/libmqic.so -o myrunner

Following output should be seen after the execution on the above statement:

Reading specs from /usr/local/lib/gcc/sparc-sun-solaris2.10/3.4.6/specs
Configured with: ../configure --with-as=/usr/ccs/bin/as --with-ld=/usr/ccs/bin/ld --enable-shared --enable-languages=c,c++,f77
Thread model: posix
gcc version 3.4.6
 /usr/local/libexec/gcc/sparc-sun-solaris2.10/3.4.6/cc1 -quiet -v -I/usr/informix/incl/tools -I/usr/informix/incl/esql -I/opt/mqm/inc -D__arch64__ -D__sparcv9 fgiusr.c -mptr64 -mstack-bias -mno-v8plus -mcpu=v9 -quiet -dumpbase fgiusr.c -m64 -auxbase fgiusr -version -o /var/tmp//ccNzNEmS.s
ignoring nonexistent directory "NONE/include"
ignoring nonexistent directory "/usr/local/lib/gcc/sparc-sun-solaris2.10/3.4.6/../../../../sparc-sun-solaris2.10/include"
#include "..." search starts here:
#include <...> search starts here:
 /usr/informix/incl/tools
 /usr/informix/incl/esql
 /opt/mqm/inc
 /usr/local/include
 /usr/local/lib/gcc/sparc-sun-solaris2.10/3.4.6/include
 /usr/include
End of search list.
GNU C version 3.4.6 (sparc-sun-solaris2.10)
        compiled by GNU C version 3.3.2.
GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
 /usr/ccs/bin/as -V -Qy -s -xarch=v9 -o /var/tmp//cc4f9CWC.o /var/tmp//ccNzNEmS.s
/usr/ccs/bin/as: Sun Compiler Common 10 Patch 09/04/2007
 /usr/local/libexec/gcc/sparc-sun-solaris2.10/3.4.6/cc1 -quiet -v -I/usr/informix/incl/tools -I/usr/informix/incl/esql -I/opt/mqm/inc -D__arch64__ -D__sparcv9 myprogram.c -mptr64 -mstack-bias -mno-v8plus -mcpu=v9 -quiet -dumpbase myprogram.c -m64 -auxbase mqfunc -version -o /var/tmp//ccNzNEmS.s
ignoring nonexistent directory "NONE/include"
ignoring nonexistent directory "/usr/local/lib/gcc/sparc-sun-solaris2.10/3.4.6/../../../../sparc-sun-solaris2.10/include"
#include "..." search starts here:
#include <...> search starts here:
 /usr/informix/incl/tools
 /usr/informix/incl/esql
 /opt/mqm/inc
 /usr/local/include
 /usr/local/lib/gcc/sparc-sun-solaris2.10/3.4.6/include
 /usr/include
End of search list.
GNU C version 3.4.6 (sparc-sun-solaris2.10)
        compiled by GNU C version 3.3.2.
GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
 /usr/ccs/bin/as -V -Qy -s -xarch=v9 -o /var/tmp//ccv77fcB.o /var/tmp//ccNzNEmS.s
/usr/ccs/bin/as: Sun Compiler Common 10 Patch 09/04/2007
 /usr/local/libexec/gcc/sparc-sun-solaris2.10/3.4.6/collect2 -V -Y P,/usr/lib/sparcv9 -Qy -o fglmq /usr/local/lib/gcc/sparc-sun-solaris2.10/3.4.6/sparcv9/crt1.o /usr/local/lib/gcc/sparc-sun-solaris2.10/3.4.6/sparcv9/crti.o /usr/ccs/lib/sparcv9/values-Xa.o /usr/local/lib/gcc/sparc-sun-solaris2.10/3.4.6/sparcv9/crtbegin.o -L/usr/informix/lib -L/usr/informix/lib/esql -L/usr/informix/lib/lib/tools -L/usr/local/lib/gcc/sparc-sun-solaris2.10/3.4.6/sparcv9 -L/usr/local/lib/gcc/sparc-sun-solaris2.10/3.4.6 -L/usr/ccs/bin/sparcv9 -L/usr/ccs/bin -L/usr/ccs/lib/sparcv9 -L/usr/ccs/lib -L/usr/local/lib/gcc/sparc-sun-solaris2.10/3.4.6/../../../sparcv9 -L/usr/local/lib/gcc/sparc-sun-solaris2.10/3.4.6/../../.. -L/lib/sparcv9 -L/usr/lib/sparcv9 /var/tmp//cc4f9CWC.o /var/tmp//ccv77fcB.o /opt/mqm/lib64/libmqic.so /usr/informix/lib/tools/libfmain.a /usr/informix/lib/tools/libfglgo.a /usr/informix/lib/tools/lib4gl.a /usr/informix/lib/tools/lib4io.a /usr/informix/lib/tools/libnmenu.a /usr/informix/lib/tools/lib4io.a /usr/informix/lib/tools/librdsterm.a /usr/informix/lib/tools/libfmain.a /usr/informix/lib/tools/libfe.a /usr/informix/lib/tools/libfmain.a -ltermlib -liffgisql -lifasf -lifgen -lifos -lifgls -lnsl -lsocket -ldl -lm /usr/informix/lib/esql/checkapi.o -lifglx -laio -lm -ldl -lelf -ltermlib -lgcc -lgcc_eh -lc -lgcc -lgcc_eh -lc /usr/local/lib/gcc/sparc-sun-solaris2.10/3.4.6/sparcv9/crtend.o /usr/local/lib/gcc/sparc-sun-solaris2.10/3.4.6/sparcv9/crtn.o
ld: Software Generation Utilities - Solaris Link Editors: 5.10-1.1518

The final output of this will generate a custom runner called myrunner. This runner will contain the required C implementation that is needed to execute a 4GL program. On 4GL site, the program must compile using fglpc in order to link with the runner. Assuming the the_4gl_program.4gl has successfully compile into the_4gl_program.4go, this would be the step to launch 4GL program:

myrunner the_4gl_program