awk to reorder lines in file

Shell Programming and Scripting
1

The output of an awk script is the below file . Line 1,3 that starts with the Ion... need to be under line 2,4 that starts with R_ . The awk runs but no output results. Thank you :).

file

IonXpress_007 MEV37
R_2016_09_20_12_47_36_user_S5-00580-7-Medexome
IonXpress_007 MEV40
R_2016_09_20_12_47_36_user_S5-00580-8-Medexome

desired output

R_2016_09_20_12_47_36_user_S5-00580-7-Medexome
IonXpress_007 MEV37
R_2016_09_20_12_47_36_user_S5-00580-8-Medexome
IonXpress_007 MEV40

awk

awk 'BEGIN{split("R_",n)} {a[NR]=$0} END{for(i=1;i in n;i++) print a[n]}' file
2

Hello cmccabe,

Could you please try following and let me know if this helps you.

awk '/^Ion/{A=$0;next} /^R_/{print $0 ORS A;A=""}'  Input_fie

Output will be as follows.

R_2016_09_20_12_47_36_user_S5-00580-7-Medexome
IonXpress_007 MEV37
R_2016_09_20_12_47_36_user_S5-00580-8-Medexome
IonXpress_007 MEV40

Thanks,
R. Singh

1 Like
3

Hi,

If input file contents are same as in post#1, please try the following one:

awk '/IonXpress_007/{x=$0;getline;print $0"\n"x}' file

you need to consider RavinderSingh13 solution, if you want to check if line starts with R_ for example.

Adding sed solution:

sed -ne '/IonXpress_007/{x;n;/^R_/{p};x;p}' file

cat file
IonXpress_007 MEV37
R_2016_09_20_12_47_36_user_S5-00580-7-Medexome
IonXpress_007 MEV40
R_2016_09_20_12_47_36_user_S5-00580-8-Medexome

output is:

R_2016_09_20_12_47_36_user_S5-00580-7-Medexome
IonXpress_007 MEV37
R_2016_09_20_12_47_36_user_S5-00580-8-Medexome
IonXpress_007 MEV40
1 Like
4

Hello cmccabe,

If you want to tackle this problem with an array(where our Input_file in which line starts from Ion comes on each odd line of Input_file and R_ comes into each even line of Input_file), following may help you in same too.

awk '{A[FNR]=$0} END{for(i=1;i<=FNR;i+=2){if(A[i+1]){print A[i+1]};if(A){print A}}}'   Input_file

Output will be as follows.

R_2016_09_20_12_47_36_user_S5-00580-7-Medexome
IonXpress_007 MEV37
R_2016_09_20_12_47_36_user_S5-00580-8-Medexome
IonXpress_007 MEV40

Thanks,
R. Singh

1 Like
5

Thank you both very much:).

6

If you just want to switch the order of pairs of lines in file using awk , you could also try:

awk 'NR%2{s=$0;next}{print $0 ORS s}' file

As always, if someone wants to try this on a Solaris/SunOS system, change awk to /usr/xpg4/bin/awk or nawk .

1 Like
7

Thank you all :).