With gawk, you can use the match function to capture parenthesized groups. gawk ‘match($0, pattern, ary) {print ary[1]}’ example: echo “abcdef” | gawk ‘match($0, /b(.*)e/, a) {print a[1]}’ outputs cd. Note the specific use of gawk which implements the feature in question. For a portable alternative you can achieve similar results with match() and substr. … Read more
You can use shuf. On some systems at least (doesn’t appear to be in POSIX). As jleedev pointed out: sort -R might also be an option. On some systems at least; well, you get the picture. It has been pointed out that sort -R doesn’t really shuffle but instead sort items according to their hash … Read more
“-F” is a command line argument, not AWK syntax. Try: echo “1: ” | awk -F “:” ‘/1/ {print $1}’
#Getting shell variables into awk may be done in several ways. Some are better than others. This should cover most of them. If you have a comment, please leave below. v1.5 Using -v (The best way, most portable) Use the -v option: (P.S. use a space after -v or it will be less portable. E.g., awk … Read more
Print all columns: awk ‘{print $0}’ somefile Print all but the first column: awk ‘{$1=””; print $0}’ somefile Print all but the first two columns: awk ‘{$1=$2=””; print $0}’ somefile
Use the -r (or –raw-output) option to emit raw strings as output: jq -r ‘.name’ <json.txt
sed is a stream editor. It works with streams of characters on a per-line basis. It has a primitive programming language that includes goto-style loops and simple conditionals (in addition to pattern matching and address matching). There are essentially only two “variables”: pattern space and hold space. Readability of scripts can be difficult. Mathematical operations … Read more
In bash, you should be able to do: kill $(ps aux | grep ‘[p]ython csp_build.py’ | awk ‘{print $2}’) Details on its workings are as follows: The ps gives you the list of all the processes. The grep filters that based on your search string, [p] is a trick to stop you picking up the … Read more
head and pipe with tail will be slow for a huge file. I would suggest sed like this: sed ‘NUMq;d’ file Where NUM is the number of the line you want to print; so, for example, sed ’10q;d’ file to print the 10th line of file. Explanation: NUMq will quit immediately when the line number … Read more
find /home/www \( -type d -name .git -prune \) -o -type f -print0 | xargs -0 sed -i ‘s/subdomainA\.example\.com/subdomainB.example.com/g’ -print0 tells find to print each of the results separated by a null character, rather than a new line. In the unlikely event that your directory has files with newlines in the names, this still lets … Read more