Given this script
#!/bin/awk -f
{
print $1
}
It can be called like so
foo.awk foo.txt
However I would like the script to always call foo.txt. So I would like to modify the script so that it can be called without the input file, like this
foo.awk
#!/bin/awk -f
BEGIN {ARGV[ARGC++] = "foo.txt"}
{print $1}
This will add foo.txt to the end of the arguments list, as if you had put it there on the command line. This has the added bonus of allowing you to extend your script to do more than just print, without having to put everything in the BEGIN block.
I would use a shell wrapper for this:
#!/bin/bash
foo.awk foo.txt
ok, do this trick maybe? (cheat?)
#!/bin/sh
awk '{print $1}' foo.txt
you could name it as foo.awk
and then
chmod +x foo.awk
now try ./foo.awk under same directory.
EDIT
#!/bin/awk -f
BEGIN{while(getline < "/path/to/foo.txt")print $1 }
strange requirement. why bash wrapper doesn't fit your requirement? You did tag the question with shell
anyway, the above script should be what you need.
Related
I have a file with some bash functions that I can call with user-defined options like this
transfer -R --src /opstk/ --dst /media/hagbard/hc1/
I also have a number of awk functions in an awk file. Would one be able to to the same with awk scripts, calling the awk file with options to do something rather than another.
awk -f replace.awk -R --src /opstk/ --dst /media/hagbard/hc1/
I understand that it is possible to include command line options for awk commands, in what context would they be useful?
I have a awk program add_hashtag.awk
BEGIN{printf("#")}1
and a bash program
for file in *.asc; do awk -f add_hashtag.awk "$file" > "$file"_in; done
that add hashtag into file. It works, however, I would like to get files with same names. When I run
for file in *.asc; do awk -f add_hashtag.awk "$file" > "$file"; done
I get files only with #.
How to do that? Thank you
Could you please try following.
for file in *.asc; do awk -f add_hashtag.awk "$file" > "temp_file" && mv "temp_file" "$file"; done
I am going with approach where creating a temp_file for output and later renaming it to Input_file so that there will not be any danger of losing or truncating actual Input_file. Also it will not rename temp_file to actual Input_file until/unless awk command is a success(with use of &&)
With gawk 4.1.0 version or so try(haven't tested it since no samples were given):
awk -i inplace -f add_hashtag.awk *.asc
OR in case you want to inplace edit files along with taking their backup:
awk -i inplace -v INPLACE_SUFFIX=.backup -f add_hashtag.awk *.asc
Gawk 5.0.0 was released on April 12, 2019. Going through the announcement I found this:
Changes from 4.2.1 to 5.0.0
(...) 11. Namespaces have been implemented! See the manual. One consequence of this is that files included with -i, read with -f, and command line program segments must all be self-contained syntactic units. E.g., you can no longer do something like this:
gawk -e 'BEGIN {' -e 'print "hello" }'
I was curious about this behaviour that is no longer supported, but unfortunately my Gawk 4.1.3 did not offer much output out of it:
$ gawk -e 'BEGIN {' -e 'print "hello" }'
gawk: cmd. line:1: BEGIN {
gawk: cmd. line:1: ^ unexpected newline or end of string
From what I see in the manual of GAWK 4.2, the -e option was marked as problematic already:
GNU Awk User's Guide, on Options
-e program-text
--source program-text
Provide program source code in the program-text. This option allows you to mix source code in files with source code that you enter on the command line. This is particularly useful when you have library functions that you want to use from your command-line programs (see AWKPATH Variable).
Note that gawk treats each string as if it ended with a newline character (even if it doesn’t). This makes building the total program easier.
CAUTION: At the moment, there is no requirement that each program-text be a full syntactic unit. I.e., the following currently works:
$ gawk -e 'BEGIN { a = 5 ;' -e 'print a }'
-| 5
However, this could change in the future, so it’s not a good idea to rely upon this feature.
But, again, this fails in my console:
$ gawk -e 'BEGIN {a=5; ' -e 'print a }'
gawk: cmd. line:1: BEGIN {a=5;
gawk: cmd. line:1: ^ unexpected newline or end of string
So what is gawk -e 'BEGIN {' -e 'print "hello" }' doing exactly on Gawk < 5?
It's doing just what you'd expect - concatenating the parts to form gawk 'BEGIN {print "hello" }' and then executing it. You can actually see how gawk is combining the code segments by pretty-printing it:
$ gawk -o- -e 'BEGIN {' -e 'print "hello" }'
BEGIN {
print "hello"
}
That script isn't useful to be written in sections and concatenated but if you consider something like:
$ cat usea.awk
{ a++ }
$ echo foo | gawk -e 'BEGIN{a=5}' -f usea.awk -e 'END{print a}'
6
then you can see the intended functionality might be useful for mixing some command-line code with scripts stored in files to run:
$ gawk -o- -e 'BEGIN{a=5}' -f usea.awk -e 'END{print a}'
BEGIN {
a = 5
}
{
a++
}
END {
print a
}
i have this file content in my sample file "haproxy-monitoring.conf"
[[inputs.haproxy]]
servers = ["http://localhost:31330/haproxy?stats" ]
Can you please help me, how I can extract just the port number '31330' from the file haproxy-monitoring.conf in a bash script.
with sed
$ sed -rn '/servers/s/.*:([0-9]+).*/\1/p' file
or similarly with awk
$ awk '/servers/{print gensub(/.*:([0-9]+).*/,"\\1",1)}' file
awk -F'[:/]' '{print $5}' file
31330
Or something like
grep -Eo '[0-9]+' file
Questions that state what the output should be without explaining why it should be that leave you open to all sorts of answers unrelated to what you really are trying to do. idk if this is what you want or not since you haven't told us:
$ tr -cd '0-9' < file
31330
I am running the following command using awk on file.txt ,currently its running the command on the ids present in file.txt from top to bottom..i want the commmand to be run in the reverse order for the ids present in file.txt..any inputs on how we can do this?
git command $(awk '{print $1}' file.txt)
file.txt contains.
97a65fd1d1b3b8055edef75e060738fed8b31d3
fb8df67ceff40b4fc078ced31110d7a42e407f16
a0631ce8a9a10391ac4dc377cd79d1adf1f3f3e2
.....
If you aren't bound to using awk then tail with the -r (for reverse) argument will do the trick...
myFile.txt
97a65fd1d1b3b8055edef75e060738fed8b31d3
fb8df67ceff40b4fc078ced31110d7a42e407f16
a0631ce8a9a10391ac4dc377cd79d1adf1f3f3e2
Now to print it in reverse...
$ tail -r myFile.txt
a0631ce8a9a10391ac4dc377cd79d1adf1f3f3e2
fb8df67ceff40b4fc078ced31110d7a42e407f16
97a65fd1d1b3b8055edef75e060738fed8b31d3
EDIT:
To output this to a file simply redirect it out...
$ tail -r myFile.txt > newFile.txt
EDIT:
Want to write to the same file? No problem!
tail -r myFile.txt > temp.txt; cat temp.txt > myFile.txt; rm temp.txt;
For some reason when I redirected tail -r to the same file it came back blank, this workaround avoids that issue by writing to a temporary "buffer" file.
To reverse the lines in a file using awk, use
awk '{a[i++]=$0} END {for (j=i-1; j>=0;) print a[j--] }' file
use $1 instead of $0 above to operate on the first field only instead of the whole line.