Do you have a method to quickly remove the first line of a file in bash shell ? I mean using sed or stuff like that.


One-liners in reverse order of length, portable unless noted.

sed (needs GNU sed for -i):

sed -i 1d file

ed (needs e.g. bash for $'...' expansion and here string):

ed file <<< $'1d\nw\nq'


awk NR\>1 infile > outfile


tail -n +2 infile > outfile

read + cat:

(read x; cat > outfile) < infile

bash built-ins:

while IFS= read -r; do ((i++)) && printf %s\\n "$REPLY" >> outfile; done < infile
  • 4
    or ed file1 <<< $'1d\nw\nq' – glenn jackman May 16 '11 at 14:58
  • 1
    In my case, tail is 15 times slower than sed. tail needs 13.5s, sed needs 0.85s. My file has ~1M lines, ~100MB. MacBook Air 2013 with SSD. – jcsahnwaldt Reinstate Monica Feb 1 '16 at 16:26
$ tail -n +2 <<< $'1\n2\n3'
| improve this answer | |

Using dd

fll=$(( $(head -n 1 $fn | wc -c) + 1))
dd if="$fn" of="${fn}.out" bs=1M iflags=skip_bytes skip=$fll
echo "Files differ by $(( $(find $fn* -printf "%s - \n" ; echo "0") )) bytes. First line of $fn is $fll bytes."

Add any iflags= and oflags= you might need - with commas separating them.

| improve this answer | |

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