If you quickly learn the basics of awk, you can indeed do amazing things on the command line. But the real reason to learn awk is to have an excuse to read the superb book The AWK Programming Language by Aho, Kernighan, and Weinberger. The AWK Programming Language at archive.org You would think, from the … Read more
Update Here is a solution from yottatsa on a similar question that only does replacement for variables like $VAR or ${VAR}, and is a brief one-liner i=32 word=foo envsubst < template.txt Of course if i and word are in your environment, then it is just envsubst < template.txt On my Mac it looks like it … Read more
I assume you want lowercase the text. Solution is pretty simple: ggVGu Explanation: gg – goes to first line of text V – turns on Visual selection, in line mode G – goes to end of file (at the moment you have whole text selected) u – lowercase selected area
The delimiter can be a regular expression. awk -F'[/=]’ ‘{print $3 “\t” $5 “\t” $8}’ file Produces: tc0001 tomcat7.1 demo.example.com tc0001 tomcat7.2 quest.example.com tc0001 tomcat7.5 www.example.com
A sed script that will only replace the first occurrence of “Apple” by “Banana” Example Input: Output: Apple Banana Apple Apple Orange Orange Apple Apple This is the simple script: Editor’s note: works with GNU sed only. sed ‘0,/Apple/{s/Apple/Banana/}’ input_filename The first two parameters 0 and /Apple/ are the range specifier. The s/Apple/Banana/ is what … Read more
Use shuf with the -n option as shown below, to get N random lines: shuf -n N input > output
# If you want to edit the file in-place sed -i -e ‘s/^/prefix/’ file # If you want to create a new file sed -e ‘s/^/prefix/’ file > file.new If prefix contains /, you can use any other character not in prefix, or escape the /, so the sed command becomes ‘s#^#/opt/workdir#’ # or ‘s/^/\/opt\/workdir/’
sed -n ‘16224,16482p;16483q’ filename > newfile From the sed manual: p – Print out the pattern space (to the standard output). This command is usually only used in conjunction with the -n command-line option. n – If auto-print is not disabled, print the pattern space, then, regardless, replace the pattern space with the next line … Read more