Swap the appearance order of two lines if needed.
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From: Hongyi Zhao on 24 Nov 2009 04:34 Hi all, I want to swap the appearance order of two lines in a file if needed. For detail, please see the following minimal example: .... here_comes_line_b .... here_comes_line_a .... Suppose the following should be the final result I want: .... here_comes_line_a .... here_comes_line_b .... Furthermore, in my file, line_a and line_b only occur once. What code should I use? -- ..: Hongyi Zhao [ hongyi.zhao AT gmail.com ] Free as in Freedom :.
From: WANG Cong on 24 Nov 2009 08:05 On Tue, 24 Nov 2009 17:34:47 +0800, Hongyi Zhao wrote: > Hi all, > > I want to swap the appearance order of two lines in a file if needed. > For detail, please see the following minimal example: > > ... > here_comes_line_b > ... > here_comes_line_a > ... > > > Suppose the following should be the final result I want: > > ... > here_comes_line_a > ... > here_comes_line_b > ... > > Furthermore, in my file, line_a and line_b only occur once. > > What code should I use? perl -e '@_ = <STDIN>; ($_[$ARGV[0]-1], $_[$ARGV[1]-1])=($_[$ARGV[1]-1], $_[$ARGV[0]-1]); print @_;' `grep -n here_comes_line_b your_file | cut - d: -f1` `grep -n here_comes_line_a your_file | cut -d: -f1` < your_file
From: Ed Morton on 24 Nov 2009 08:12 Hongyi Zhao wrote: > Hi all, > > I want to swap the appearance order of two lines in a file if needed. > For detail, please see the following minimal example: > > ... > here_comes_line_b > ... > here_comes_line_a > ... > > > Suppose the following should be the final result I want: > > ... > here_comes_line_a > ... > here_comes_line_b > ... > > Furthermore, in my file, line_a and line_b only occur once. > > What code should I use? Either use an array to hold the whole file: awk '{file[NR]=$0} /here_comes_line_a|here_comes_line_b/{swap[++cnt]=NR} END{ tmp=file[swap[1]]; file[swap[1]]=file[swap[2]]; file[swap[2]]=tmp for (i=1;i<=NR;i++) print file[i] }' file or do two passes of the file: awk 'NR==FNR{ if (/here_comes_line_a/) a[NR]=$0 else if (/here_comes_line_b/) b[NR]=$0 next } NR in a { $0 = b[NR] } NR in b { $0 = a[NR] } 1' file file Both untested. Regards, Ed.
From: Glenn Jackman on 24 Nov 2009 10:12 At 2009-11-24 08:12AM, "Ed Morton" wrote: > Hongyi Zhao wrote: > > Hi all, > > > > I want to swap the appearance order of two lines in a file if needed. > > For detail, please see the following minimal example: > > > > ... > > here_comes_line_b > > ... > > here_comes_line_a > > ... > > > > > > Suppose the following should be the final result I want: > > > > ... > > here_comes_line_a > > ... > > here_comes_line_b > > ... > > > > Furthermore, in my file, line_a and line_b only occur once. > > > > What code should I use? > > Either use an array to hold the whole file: > > awk '{file[NR]=$0} /here_comes_line_a|here_comes_line_b/{swap[++cnt]=NR} > END{ tmp=file[swap[1]]; file[swap[1]]=file[swap[2]]; file[swap[2]]=tmp > for (i=1;i<=NR;i++) print file[i] }' file > > or do two passes of the file: > > awk 'NR==FNR{ if (/here_comes_line_a/) a[NR]=$0 > else if (/here_comes_line_b/) b[NR]=$0 > next > } > NR in a { $0 = b[NR] } > NR in b { $0 = a[NR] } > 1' file file > > Both untested. Or, in one pass, store just line_b and the intermediate lines: awk ' BEGIN { lineb = ""; counter = 0 } /here_comes_line_b/ { lineb = $0; next } /here_comes_line_a/ { for (i = 1; i <= counter; i++) {print store[i]} print lineb lineb = "" next } lineb != "" { store[++counter] = $0; next } 1 {print} ' file -- Glenn Jackman Write a wise saying and your name will live forever. -- Anonymous
From: Rakesh Sharma on 24 Nov 2009 15:22 On Nov 24, 2:34 pm, Hongyi Zhao <hongyi.z...(a)gmail.com> wrote: > Hi all, > > I want to swap the appearance order of two lines in a file if needed. > For detail, please see the following minimal example: > > ... > here_comes_line_b > ... > here_comes_line_a > ... > > Suppose the following should be the final result I want: > > ... > here_comes_line_a > ... > here_comes_line_b > ... > > Furthermore, in my file, line_a and line_b only occur once. > > What code should I use? > -- > .: Hongyi Zhao [ hongyi.zhao AT gmail.com ] Free as in Freedom :. Provided there's atleast one line between line_a & line_b we can do this: sed -e ' /\n/b /re1/,/re2/!b /re2/!H;/re1/h;/re2/!d p;g;s/\n.*//;H;g;D ' yourfile
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