I'm currently trying to find a line in a file
#define IMAX 8000
and replacing 8000 with another number.
Currently, stuck trying to pipe arguments from awk into sed.
grep '#define IMAX' 1d_Euler_mpi_test.c | awk '{print $3}' | sed
Not too sure how to proceed from here.
I would do something like:
sed -i '' '/^#define IMAX 8000$/s/8000/NEW_NUMBER/' 1d_Euler_mpi_test.c
Could you please try following. Place new number's value in place of new_number too.(tested this with GNU sed)
echo "#define IMAX 8000" | sed -E '/#define IMAX /s/[0-9]+$/new_number/'
In case you are reading input from an Input_file and want to save its output into Input_file itself use following then.
sed -E '/#define IMAX /s/[0-9]+$/new_number/' Input_file
Add -i flag in above code in case you want to save output into Input_file itself. Also my codes will catch any digits which are coming at the end of the line which has string #define IMAX so in case you only want to look for 8000 or any fixed number change [0-9]+$ to 8000 etc in above codes then.
You may use GNU sed.
sed -i -e 's/IMAX 8000/IMAX 9000/g' /tmp/file.txt
Which will invoke sed to do an in-place edit due to the -i option. This can be called from bash.
If you really really want to use just bash, then the following can work:
while read a ; do echo ${a//IMAX 8000/IMAX 9000} ; done < /tmp/file.txt > /tmp/file.txt.t ; mv /tmp/file.txt{.t,}
This loops over each line, doing a substitution, and writing to a temporary file (don't want to clobber the input). The move at the end just moves temporary to the original name.
IMAX 9000?
-i implies GNU sed. The question didn't specify a variant. For that reason and to retain value to a wider audience, you might want to provide more portable usage, or at least clarify that what tooling is required to make use of your answer.