Login or Register to Ask a Question and Join Our Community


Shell Programming and Scripting

Tracing a function call

Login to Discuss or Reply to this Discussion in Our Community

 
Thread Tools Search this Thread
Top Forums Shell Programming and Scripting Tracing a function call
# 1  
Old 03-19-2010
Tracing a function call
Hi

I am hoping someone can explain this to me as I am struggling to understand it.

I had a problem today with needing to trace a ksh script that was dotting in a function that was writing to stdout. The problem was it was being run in a sub shell and the output was being parsed by the calling script so I could not have any trace output on stdout.

On a hunch I tried this solution to log the function's trace to file and it worked but I don't know why, can anyone enlighten me?

The code: -

Code:
TX5XN:/home/brad/ksh_stuff>cat trace_2

func()
{
    set -x
    echo "This goes to stdout from func"
    set +x
    echo "=============================" >&2
} 2>> set.log2

echo "This goes to stdout from main body"

for x in 1 2 3 4 5
do
    func
done

The output to stdout: -

Code:
TX5XN:/home/brad/ksh_stuff> trace_2  
This goes to stdout from main body
This goes to stdout from func
This goes to stdout from func
This goes to stdout from func
This goes to stdout from func
This goes to stdout from func

The trace log: -

Code:
TX5XN:/home/brad/ksh_stuff>cat set.log2
trace_2:5-echo 'This goes to stdout from func'
=============================
trace_2:5-echo 'This goes to stdout from func'
=============================
trace_2:5-echo 'This goes to stdout from func'
=============================
trace_2:5-echo 'This goes to stdout from func'
=============================
trace_2:5-echo 'This goes to stdout from func'
=============================

# 2  
Old 03-19-2010
Hi:

Your code redirects stderr for the function to set.log2, so that's where all the trace output will be found. If the calling script is only reading stdout (from a pipe or coprocesses or fifo), you don't need that redirection.

Quote:
-x
The shell shall write to standard error a trace for each command after it expands the command and before it executes it. It is unspecified whether the command that turns tracing off is traced.
-- Shell Command Language

Regards,
Alister
Login or Register to Ask a Question

Previous Thread | Next Thread

10 More Discussions You Might Find Interesting

1. Shell Programming and Scripting

How to Call a Function

Hi I have created a function in a Shell Script test.sh function fnTest() { echo "My first Method } I have called this function in my test.sh cat abc.txt | grep "test" echo " test" fnTest But while running the shell script i got the following error: ... (2 Replies)
Discussion started by: nanthagopal
2 Replies

2. Shell Programming and Scripting

After exit from function it should not call other function

Below is my script that is function properly per my conditions but I am facing one problem here that is when one function fails then Iy should not check other functions but it calls the other function too So anyone can help me how could i achieve this? iNOUT i AM GIVING TO THE... (1 Reply)
Discussion started by: rohit22hamirpur
1 Replies

3. Infrastructure Monitoring

diffrence between method call and function call in perl

Hello, I have a problem with package and name space. require "/Mehran/DSGateEngineLib/general.pl"; use strict; sub System_Status_Main_Service_Status_Intrusion_Prevention { my %idpstatus; my @result; &General_ReadHash("/var/dsg/idp/settings",\%idpstatus); #print... (4 Replies)
Discussion started by: Zaxon
4 Replies

4. Shell Programming and Scripting

Function Call

Hi, I have a string corresponding to a function. How I can call that function without if statement? Thanks in advance. (4 Replies)
Discussion started by: Zaxon
4 Replies

5. Programming

tracing function with Graphviz

I was searching for a tool to trace the function flow to help me understand the code. I came across the article "visualize function calls with graphviz" by Tim Jones. Visualize function calls with Graphviz I was able to obtain the flow diagram for simple programs and also for the example... (0 Replies)
Discussion started by: cjjoy
0 Replies

6. Programming

Tracing Function Calls in a program

Apart from writing debug and statements in constructors is there any way by which we can trace the function call stack at any depth? The issue that we always face is that when program crashes (Web Server running on Linux) we have no idea where it crashes and we have to do the hard way of... (1 Reply)
Discussion started by: uunniixx
1 Replies

7. Shell Programming and Scripting

help on function call

hello, when i call function inside awk traitement it doesn't work, i don't have error execution but i don't get result and if i call the function outside awk traitement it work well.. there's something special in awk call function?? here is the example : awk -F "," '{ {first=$1; sec=$2;... (3 Replies)
Discussion started by: kamel.seg
3 Replies

8. Shell Programming and Scripting

function call

hi, can any one help me to correct this function call. awk -F "," '{ {first=$1; sec=$2; tro=$3;quat=$4 } if (tro == "") { $3 = search "$file2" "$first" "$file3" {print $1","$2","$3","$4} } else {print $1","$2","$3 $4}}' $file1 > $file search () { (2 Replies)
Discussion started by: kamel.seg
2 Replies

9. Shell Programming and Scripting

call function

I have a function check_ok in my abc.sh. which return me 1 or 0 . I want to call this fuction through other shell script. this shell also send two parameter to calling function. Can you please tell me how. I am very new in unix. #!/bin/bash date_equal() { sqlplus -silent... (4 Replies)
Discussion started by: Jamil Qadir
4 Replies

10. Programming

Help with a function call

Hi, Can anyone help me figure out the problem I'm having with a function call? I have a header file, which sets an enum: typedef enum {INFO, WARNING, FATAL} Levels; int log_event (Levels, char *fmt, ...); ..then the function is called this way: log_event(INFO, "Message text"); ... (6 Replies)
Discussion started by: Stevhp
6 Replies
Login or Register to Ask a Question