Shell Programming and Scripting

Hi, im trying to make a script which will look up every .c file in the current directory for the strings printf or fprintf. if found, the script adds the statement #include <stdio.h> at the beginning of the file but only if it doesnt alrdy have it included. How do i do that ?i know firstly, i need to do
grep -e "printf" -e "fprintf" *.c . then i dont know if i need to grep #include <stdio.h> or sed . plz help me . thx in advance.

Code:

check whether printf or fprintf is there or not in the file
if there 
  check if #include header file is there or not
  if there
    leave it
  if not there
    add the needed lines
if not there
  skip to next file and proceed from that

how do i add #include <stdio.h> to the file by using sed ?
do i use sed to add this line to the screen and send the output to a file ,then move the file to the .c file? plz help

Either way is possible

redirecting the modified output to a file and then renaming

Code:

sed '1i\
text to insert' < input_file > tmp
mv tmp input_file

or doing an in-place edit with -i option

Code:

sed -i '1i\
text to insert' < input_file

Do something like

Code:

first=$(grep -m 1 "#include" test.c)
sed -e "s/$first/&\n#include <stdio.h>/" test.c

If you have the -i flag available for sed, use that. Else redirect to another file and then rename it.

#!/bin/bash
grep -e "printf" -e "fprintf" *.c;
if[ $? = "0" ]; then
grep -e "#include <stdio.h>";
if [ $? = "0" ];then
sed 'li\#include <stdio.h>' < *.c > temp;
mv temp *.c;
fi
fi

it says syntax error , i dont know how to fix it, plz help
and does *.c in sed mean that all file with .c or they are .c file with printf or fprint but #include?

search for example posts posted here.

You are checking for all the files in one shot.

Make the check for one file at a time. Use looping for the list of files

input stream to be specified for grep