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copied!<p>Here is what I usually do on AIX:</p> <pre><code>before=2 << The number of lines to be shown Before >> after=2 << The number of lines to be shown After >> grep -n <pattern> <filename> | cut -d':' -f1 | xargs -n1 -I % awk "NR<=%+$after && NR>=%-$before" <filename> </code></pre> <p>If you do not want the extra 2 varialbles you can always use it an a one line:</p> <pre><code>grep -n <pattern> <filename> | cut -d':' -f1 | xargs -n1 -I % awk 'NR<=%+<<after>> && NR>=%-<<before>>' <filename> </code></pre> <p>Suppose I have a pattern 'stack' and the filename is flow.txt I want 2 lines before and 3 lines after. The the command will be like:</p> <pre><code>grep -n 'stack' flow.txt | cut -d':' -f1 | xargs -n1 -I % awk 'NR<=%+3 && NR>=%-2' flow.txt </code></pre> <p>I want 2 lines before and only - the the command will be like:</p> <pre><code>grep -n 'stack' flow.txt | cut -d':' -f1 | xargs -n1 -I % awk 'NR<=% && NR>=%-2' flow.txt </code></pre> <p>I want 3 lines after and only - the the command will be like:</p> <pre><code>grep -n 'stack' flow.txt | cut -d':' -f1 | xargs -n1 -I % awk 'NR<=%+3 && NR>=%' flow.txt </code></pre> <p>Multiple Files - change it for Awk & grep. From above for the pattern 'stack' with the filename is <strong>flow.*</strong> - 2 lines before and 3 lines after. The the command will be like: </p> <pre><code> awk 'BEGIN { before=1; after=3; pattern="stack"; i=0; hold[before]=""; afterprints=0} { #Print the lines from the previous Match if (afterprints > 0) { print FILENAME ":" FNR ":" $0 afterprints-- #keep a track of the lines to print after - this can be reset if a match is found if (afterprints == 0) print "---" } #Look for the pattern in current line if ( match($0, pattern) > 0 ) { # print the lines in the hold round robin buffer from the current line to line-1 # if (before >0) => user wants lines before avoid divide by 0 in % # and afterprints => 0 - we have not printed the line already for(j=i; j < i+before && before > 0 && afterprints == 0 ; j++) print hold[j%before] if (afterprints == 0) # print the line if we have not printed the line already print FILENAME ":" FNR ":" $0 afterprints=after } if (before > 0) # Store the lines in the round robin hold buffer { hold[i]=FILENAME ":" FNR ":" $0 i=(i+1)%before } }' flow.* </code></pre>

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