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comparison tools/unix_tools/remove_ending.sh @ 0:9071e359b9a3

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author xuebing
date Fri, 09 Mar 2012 19:37:19 -0500
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-1:000000000000 0:9071e359b9a3
1 #!/bin/sh
2
3 # Version 0.1 , 15aug08
4 # Written by Assaf Gordon (gordon@cshl.edu)
5 #
6
7 LINES="$1"
8 INFILE="$2"
9 OUTFILE="$3"
10
11 if [ "$LINES" == "" ]; then
12 cat >&2 <<EOF
13 Remove Ending Lines
14
15 Usage: $0 LINES [INFILE] [OUTFILE]
16
17 LINES - number of lines to remove from the end of the file
18 [INFILE] - input file (if not specified - defaults to STDIN)
19 [OUTFILE]- output file (if not specified - defaults to STDOUT)
20
21 Input Example:
22
23 #Chr Start End
24 chr1 10 15
25 chr1 40 20
26 chr1 21 14
27 total 3 chromosomes
28
29 Removing 1 line (the last line) produces:
30
31 #Chr Start End
32 chr1 10 15
33 chr1 20 40
34 chr 14 21
35
36 Usage Example:
37
38 \$ $0 1 < my_input_file.txt > my_output_file.txt
39
40 EOF
41
42 exit 1
43 fi
44
45 #Validate line argument - remove non-digits characters
46 LINES=${LINES//[^[:digit:]]/}
47
48 #Make sure the line strings isn't empty
49 #(after the regex above, they will either contains digits or be empty)
50 if [ -z "$LINES" ]; then
51 echo "Error: bad line value (must be numeric)" >&2
52 exit 1
53 fi
54
55 # Use default (stdin/out) values if infile / outfile not specified
56 [ -z "$INFILE" ] && INFILE="/dev/stdin"
57 [ -z "$OUTFILE" ] && OUTFILE="/dev/stdout"
58
59 #Make sure the input file (if specified) exists.
60 if [ ! -r "$INFILE" ]; then
61 echo "Error: input file ($INFILE) not found!" >&2
62 exit 1
63 fi
64
65
66 # The "gunzip -f" trick allows
67 # piping a file (gzip or plain text, real file name or "/dev/stdin") to sed
68 gunzip -f <"$INFILE" | sed -n -e :a -e "1,${LINES}!{P;N;D;};N;ba" > "$OUTFILE"
69