Multiline Fasta To Single Line Fasta

I got the question, solved it, then I realized it is rather common problem. So, I googled for it and the solution, I have to admit, was better than mine. Here is the solution and link to the original source.

I have a fasta file with following format

file.fa

>gi|321257144|ref|XP_003193485.1| flap endonuclease [Cryptococcus gattii WM276]
MGIKGLTGLLSENAPKCMKDHEMKTLFGRKVAIDASMSIYQFLIAVRQQDGQMLMNESGDVTSHLMGFFY
RTIRMVDHGIKPCYIFDGKPPELKGSVLAKRFARREEAKEGEEEAKETGTAEDVDKLARRQVRVTREHNE
ECKKLLSLMGIPVVTAPGEAEAQCAELARAGKVYAAGSEDMDTLTFHSPILLRHLTFSEAKKMPISEIHL
DVALRDLEMSMDQFIELCILLGCDYLEPCKGIGPKTALKLMREHGTLGKVVEHIRGKMAEKAEEIKAAAD
EEAEAEAEAEKYDSDPENEEGGETMINSDGEEVPAPSKPKSPKKKAPAKKKKIASSGMQIPEFWPWEEAK
QLFLKPDVVNGDDLVLEWKQPDTEGLVEFLCRDKGFNEDRVRAGAAKLSKMLAAKQQGRLDGFFTVKPKE
PAAKDAGKGKGKDTKGEKRKAEEKGAAKKKTKK
>gi|321473340|gb|EFX84308.1| hypothetical protein DAPPUDRAFT_47502 [Daphnia pulex]
MGIKGLTQVIGDTAPTAIKENEIKNYFGRKVAIDASMSIYQFLIAVRSEGAMLTSADGETTSHLMGIFYR
TIRMVDNGIKPVYVFDGKPPDMKGGELTKRAEKREEASKQLVLATDAGDAVEMEKMNKRLVKVNKGHTDE
CKQLLTLMGIPYVEAPCEAEAQCAALVKAGKVYATATEDMDSLTFGSNVLLRYLTYSEAKKMPIKEFHLD
KILDGLSYTMDEFIDLCIMLGCDYCDTIKGIGAKRAKELIDKHRCIEKVIENLDTKKYTVPENWPYQEAR
RLFKTPDVADAETLDLKWTQPDEEGLVKFMCGDKNFNEERIRSGAKKLCKAKTGQTQGRLDSFFKVLPSS
KPSTPSTPASKRKVGCIIYLFLYF

but I wanna to look sequence in a single line, not in many line as they are. any quick method??

using awk:

awk '/^>/ {printf("\n%s\n",$0);next; } { printf("%s",$0);}  END {printf("\n");}' file.fa

>gi|321257144|ref|XP_003193485.1| flap endonuclease [Cryptococcus gattii WM276]
MGIKGLTGLLSENAPKCMKDHEMKTLFGRKVAIDASMSIYQFLIAVRQQDGQMLMNESGDVTSHLMGFFYRTIRMVDHGIKPCYIFDGKPPELKGSVLAKRFARREEAKEGEEEAKETGTAEDVDKLARRQVRVTREHNEECKKLLSLMGIPVVTAPGEAEAQCAELARAGKVYAAGSEDMDTLTFHSPILLRHLTFSEAKKMPISEIHLDVALRDLEMSMDQFIELCILLGCDYLEPCKGIGPKTALKLMREHGTLGKVVEHIRGKMAEKAEEIKAAADEEAEAEAEAEKYDSDPENEEGGETMINSDGEEVPAPSKPKSPKKKAPAKKKKIASSGMQIPEFWPWEEAKQLFLKPDVVNGDDLVLEWKQPDTEGLVEFLCRDKGFNEDRVRAGAAKLSKMLAAKQQGRLDGFFTVKPKEPAAKDAGKGKGKDTKGEKRKAEEKGAAKKKTKK
>gi|321473340|gb|EFX84308.1| hypothetical protein DAPPUDRAFT_47502 [Daphnia pulex]
MGIKGLTQVIGDTAPTAIKENEIKNYFGRKVAIDASMSIYQFLIAVRSEGAMLTSADGETTSHLMGIFYRTIRMVDNGIKPVYVFDGKPPDMKGGELTKRAEKREEASKQLVLATDAGDAVEMEKMNKRLVKVNKGHTDECKQLLTLMGIPYVEAPCEAEAQCAALVKAGKVYATATEDMDSLTFGSNVLLRYLTYSEAKKMPIKEFHLDKILDGLSYTMDEFIDLCIMLGCDYCDTIKGIGAKRAKELIDKHRCIEKVIENLDTKKYTVPENWPYQEARRLFKTPDVADAETLDLKWTQPDEEGLVKFMCGDKNFNEERIRSGAKKLCKAKTGQTQGRLDSFFKVLPSSKPSTPSTPASKRKVGCIIYLFLYF

Note

Note that there is a blank line at the beginning of the output - this is further discusses in the original forum post.
This example case will be discussed during the workshop