sed - only get single occurrence

Question

I am using the below SED command:

sed '/cell.* '"alatch {"'/,/^}/p' -n file

Input file is as under:

cell abc { pins on T { a b c } } cell xyz { pins on T { x y z } } cell alatch { pins on T { VSS VDDPI VDDP } pins on L { IN CT CB } pins on R { OUT } inputs { CB CT IN } outputs { OUT } } cell alatch { pins on T { VSS VDDPI VDDP } pins on L { IN CT CB } pins on R { OUT } inputs { CB CT IN } outputs { OUT } }

Output is as under:

cell alatch { pins on T { VSS VDDPI VDDP } pins on L { IN CT CB } pins on R { OUT } inputs { CB CT IN } outputs { OUT } } cell alatch { pins on T { VSS VDDPI VDDP } pins on L { IN CT CB } pins on R { OUT } inputs { CB CT IN } outputs { OUT } }

Expected out is as under:

cell alatch { pins on T { VSS VDDPI VDDP } pins on L { IN CT CB } pins on R { OUT } inputs { CB CT IN } outputs { OUT } }

What is needed is that only the first occurrence should be the output. Any suggestion for command?

Clarify the exact occurrence of what you want. Also, I don't think your quoting, while probably not incorrect, makes much sense and only obfuscates the sed command. How about '/cell.* alatch {/,/^}/p' as a start? — berndbausch
– berndbausch, Commented Feb 15, 2021 at 10:54

Kusalananda · Accepted Answer · 2021-02-15 20:33:37Z

Assuming you want the first of the two identical blocks:

$ sed '/cell alatch {/,/^}/!d; /^}/q' file cell alatch { pins on T { VSS VDDPI VDDP } pins on L { IN CT CB } pins on R { OUT } inputs { CB CT IN } outputs { OUT } }

The /cell alatch {/,/^}/ range is the range of lines that you want to get as output.

The sed expressions first deletes all lines not in this range, and then quits as soon as a } is found at the start of a line. The q instruction will cause sed to terminate after it outputs the current line, so the final } will get printed.

Executing the d instruction immediately skips to the next input line and branches back to the start of the editing script, so the q instruction has no way of executing unless it's in the range which does not cause d to execute.

With awk, achieving the same effect with code that should be reminiscent of the sed code above:

$ awk '/cell alatch {/,/^}/ { print; if ($0 ~ /^}/) exit }' file cell alatch { pins on T { VSS VDDPI VDDP } pins on L { IN CT CB } pins on R { OUT } inputs { CB CT IN } outputs { OUT } }

Actually, this is closer to the sed command

sed -n '/cell alatch {/,/^}/{ p; /^}/q; }' file

which does the same thing.

guest_7 · Accepted Answer · 2021-02-15 13:47:13Z

With awk we accumulate the desired cell data and when the depth (number of { = number of } reaches 0 we dump the cell data nd quit.

awk ' BEGIN { ORS = "" } /cell alatch \{/ {inCell=1} !inCell {next} {data = data $0 RS} /\}/ {depth--} /\{/ {depth++} !depth { print data exit } ' ./file

Using GNU sed with the same idea of the awk code above.

sed -e ' /cell alatch {/!d /\n/!{h;s/.*/x/;x;} $d;N /}$/{x;s/x//;/x/!{x;q;};x;} /{$/{x;s/$/x/;x;} s/^/\n/;D ' file

Stack Exchange Network

sed - only get single occurrence

2 Answers 2

You must log in to answer this question.

Hot Network Questions

sed - only get single occurrence

2 Answers 2

You must log in to answer this question.

Related

Hot Network Questions