UNIX for Dummies Questions & Answers

cat $X | sed "s/\<a\>/\,/g"

grep -v -F -f stopwords.txt mainfiles.txt > newfiles.txt

sed -E 's/(word1|word2|word3)/,/g'

sed -E 's/(word1|word2|word3)/,/gI'

sed -E 's/('`sed 's/,/|/g' wordlist`')/,/gI'

#!/usr/bin/env bash

# @(#) s2	Demonstrate easy replacement with perl.

# Utility functions: print-as-echo, print-line-with-visual-space, debug.
# export PATH="/usr/local/bin:/usr/bin:/bin"
LC_ALL=C ; LANG=C ; export LC_ALL LANG
pe() { for _i;do printf "%s" "$_i";done; printf "\n"; }
pl() { pe;pe "-----" ;pe "$*"; }
db() { ( printf " db, ";for _i;do printf "%s" "$_i";done;printf "\n" ) >&2 ; }
db() { : ; }
C=$HOME/bin/context && [ -f $C ] && . $C perl

FILE=${1-data1}

pl " perl code:"
cat p2

pl " Input data file $FILE:"
cat $FILE

pl " Replacement pairs, old TAB new, unpaired get \"general string\":"
cat replacements.txt

pl " Results:"
./p2 $FILE

exit 0

$ ./s2

Environment: LC_ALL = C, LANG = C
(Versions displayed with local utility "version")
OS, ker|rel, machine: Linux, 2.6.26-2-amd64, x86_64
Distribution        : Debian 5.0.8 (lenny, workstation) 
bash GNU bash 3.2.39
perl 5.10.0

-----
 perl code:
#!/usr/bin/env perl

# @(#) p2	Demonstrate replacement from hashed pairs.

use strict;
use warnings;
use Carp;

my ($f);
my $rf = "replacements.txt";
my $gs;    # general string, used if no replacement found.
$gs = "...";

# Read pairs into hash.
my (%hp);
open( $f, "<", $rf ) || croak "cannot open pairs file \"$rf\"";
my ( $t1, $t2 );
while (<$f>) {
  chomp;
  ( $t1, $t2 ) = split( /\s+/, $_, 2 );
  $hp{$t1} = defined($t2) ? $t2 : $gs;
}
close $f;

# Print hash if debugging needed.
# foreach $t1 ( keys %hp ) { print "$t1 => $hp{$t1}\n" };

# Read and replace.
while (<>) {
  foreach $t1 ( keys %hp ) {
    s/$t1/$hp{$t1}/gi;
  }
  print;
}

-----
 Input data file data1:
Now is the time
for all good men
to come to the aid
of their country.
aa aa cc bb cc bb aa AA Aa aA aa

-----
 Replacement pairs, old TAB new, unpaired get "general string":
Now	Then
is	was
good	manly
their	< yours, mine, ours >
aid	bandage
to
aa	xx
bb	yy
cc	zz

-----
 Results:
Then was the time
for all manly men
... come ... the bandage
of < yours, mine, ours > country.
xx xx zz yy zz yy xx xx xx xx xx