I am learning awk and I would like to know if there is an option to write changes to file, similar to sed where I would use -i option to save modifications to a file.
I do understand that I could use redirection to write changes. However is there an option in awk to do that?
In GNU Awk 4.1.0 (released 2013) and later, it has the option of "inplace" file editing:
[...] The "inplace" extension, built using the new facility, can be used to simulate the GNU "
sed -i" feature. [...]
Example usage:
$ gawk -i inplace '{ gsub(/foo/, "bar") }; { print }' file1 file2 file3 To keep the backup:
$ gawk -i inplace -v INPLACE_SUFFIX=.bak '{ gsub(/foo/, "bar") } > { print }' file1 file2 file3 
inplace is actually a library included with gawk according to iiSeymour's answer, so inplace is something that can be included as an includefile.
INPLACE_SUFFIX is now a namespaced variable called inplace::suffix. The extension will fall back to the old variable, but not in versions 5.0.0 and 5.0.1 (5.0.1 ships with Ubuntu 20.04 LTS), only since 5.1.0. But you can simply pass both variables to avoid any problems.
Unless you have GNU awk 4.1.0 or later...
You won't have such an option as sed's -i option so instead do:
$ awk '{print $0}' file > tmp && mv tmp file Note: the -i is not magic, it is also creating a temporary file sed just handles it for you.
As of GNU awk 4.1.0...
GNU awk added this functionality in version 4.1.0 (released 10/05/2013). It is not as straight forwards as just giving the -i option as described in the released notes:
The new -i option (from xgawk) is used for loading awk library files. This differs from -f in that the first non-option argument is treated as a script.
You need to use the bundled inplace.awk include file to invoke the extension properly like so:
$ cat file 123 abc 456 def 789 hij $ gawk -i inplace '{print $1}' file $ cat file 123 456 789 The variable INPLACE_SUFFIX can be used to specify the extension for a backup file:
$ gawk -i inplace -v INPLACE_SUFFIX=.bak '{print $1}' file $ cat file 123 456 789 $ cat file.bak 123 abc 456 def 789 hij I am happy this feature has been added but to me, the implementation isn't very awkish as the power comes from the conciseness of the language and -i inplace is 8 characters too long i.m.o.
Here is a link to the manual for the official word.
awk '{ gsub(/foo/, "bar" ) } ; { print $0 }' file > tmp.txt && mv -v tmp.txt file ?
awk '{print $0}' file | sponge file using sponge from moreutils.
mv tmp file is not in general sufficient - the file perms may have changed and must be fixed. -i inplace doesn't have this problem.just a little hack that works
echo "$(awk '{awk code}' file)" > file An alternative is to use sponge:
awk '{print $0}' your_file | sponge your_file Where you replace '{print $0}' by your awk script and your_file by the name of the file you want to edit in place.
sponge absorbs entirely the input before saving it to the file.
sponge is part of moreutils. So it won't be present by default in most systems. But looks like at least sponge itself is portable enough and can be run almost everywhere.tee-based is that sponge will read everything to RAM before writing down, hence it will freeze on large files.This can't work:
someprocess < file > file The shell performs the redirections before handing control over to someprocess (redirections). The > redirection will truncate the file to zero size (redirecting output). Therefore, by the time someprocess gets launched and wants to read from the file, there is no data for it to read.
following won't work
echo $(awk '{awk code}' file) > file this should work
echo "$(awk '{awk code}' file)" > file 
echo with -n option to avoid trailing newline.In case you want an awk-only solution without creating a temporary file and usable with version!=(gawk 4.1.0):
awk '{a[b++]=$0} END {for(c=0;c<=b;c++)print a[c]>ARGV[1]}' file 
awkcould use following link too stackoverflow.com/questions/59243104/… fyi please.