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diff --git a/LICENSE b/LICENSE
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--- /dev/null
+++ b/LICENSE
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diff --git a/README.md b/README.md
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+++ b/README.md
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+# pipetools
+
+A collection of familiar and intuitive shell tools for processing text data in a pipeline. The only dependencies are POSIX utilities such as `tr` that should be available on any POSIX-compliant system.
+
+## Examples
+
+```sh
+echo foo bar baz | words
+# Output:
+foo
+bar
+baz
+```
+
+```sh
+echo foo bar baz | words | map '$IDX $ELEM' | filter '$IDX -gt 0'
+# Output:
+1 bar
+2 baz
+```
+
+```sh
+echo foo bar baz | words | map '$IDX $ELEM' | map '$IDX $(( $X0 + 10 )) $X1'
+# Output:
+0 10 foo
+1 11 bar
+2 12 baz
+```
+
+```sh
+echo foo bar baz | words | map '$(( $IDX + 1 ))' | reduce 1 '$(( $ACC * $ELEM ))'
+# Output:
+6
+```
+
+The tools all follow the same conventions:
+
+- Input is line-based (newline-separated). You can use `words` to convert whitespace to newlines.
+- `$IDX` is the index of the element in the input stream.
+- `$ELEM` is the element itself.
+- `$X0`, `$X1`, etc. are the whitespace separated words in the current element (think columns in a table).
+- `$ACC` is the accumulator for the reduce operation.
+
+The `$(( $X0 + $X1 ))` syntax is called arithmetic expansion, which allows for basic arithmetic operations within a shell script.
+
+## Installation
+
+Copy the contents of the `tools` directory to a directory in your PATH, or run the `install.sh` script to create symlinks automatically to your selected target directory.
+
+## Author
+
+Jan Tuomi <<jan@jantuomi.fi>>
diff --git a/install.sh b/install.sh
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--- /dev/null
+++ b/install.sh
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+#!/bin/sh
+
+set -e
+
+if [ -z tools ]; then
+    echo "Error: tools directory not found. Run this script from the root directory."
+    exit 1
+fi
+
+cd tools
+
+# read TARGET without newline after prompt
+read -p "Install to? [default:/usr/local/bin] " TARGET
+
+if [ -z "$TARGET" ]; then
+    TARGET="/usr/local/bin"
+fi
+TARGET="$(eval echo "$TARGET")"
+
+(set -x; mkdir -p "$TARGET")
+
+for file in *; do
+    (set -x; ln -s "$(realpath "$file")" "$TARGET/$file") || true
+done
diff --git a/tools/each b/tools/each
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--- /dev/null
+++ b/tools/each
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+#!/bin/sh
+
+if [ -z "$1" ]; then
+    echo "Usage: $0 <command>"
+    echo ""
+    echo "Run the given command for each newline-separated line in stdin (think for-each in many programming languages)."
+    echo 'The iterator variable is called "$ELEM", and the index variable is called "$IDX".'
+    exit 1
+fi
+
+i=0
+while IFS=$'\n' read -r line; do
+    j=0
+    for item in $line; do
+        eval "X${j}='$item'"
+        j=$((j+1))
+    done
+
+    IDX=$i ELEM="$line" eval "$1"
+    i=$((i+1))
+done
diff --git a/tools/filter b/tools/filter
new file mode 100755
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--- /dev/null
+++ b/tools/filter
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+#!/bin/sh
+
+if [ -z "$1" ]; then
+    echo "Usage: $0 <command>"
+    echo ""
+    echo "Run the given test expression for each newline-separated line in stdin, and echo only the lines that return zero."
+    echo "(Think filter in many programming languages)."
+    echo 'The iterator variable is called "$ELEM", and the index variable is called "$IDX".'
+    exit 1
+fi
+
+i=0
+while IFS=$'\n' read -r line; do
+    j=0
+    for item in $line; do
+        eval "X${j}='$item'"
+        j=$((j+1))
+    done
+
+    IDX=$i ELEM="$line" eval "test $1"
+    if [ $? -eq 0 ]; then
+        echo "$line"
+    fi
+    i=$((i+1))
+done
diff --git a/tools/map b/tools/map
new file mode 100755
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--- /dev/null
+++ b/tools/map
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+#!/bin/sh
+
+if [ -z "$1" ]; then
+    echo "Usage: $0 <expr>"
+    echo ""
+    echo "Give the given expression for each newline-separated line in stdin as an argument to echo (think map in many programming languages)."
+    echo 'The iterator variable is called "$ELEM", and the index variable is called "$IDX".'
+    exit 1
+fi
+
+i=0
+while IFS=$'\n' read -r line; do
+    j=0
+    for item in $line; do
+        eval "X${j}='$item'"
+        j=$((j+1))
+    done
+
+    IDX=$i ELEM="$line" eval "echo $1"
+    i=$((i+1))
+done
diff --git a/tools/reduce b/tools/reduce
new file mode 100755
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--- /dev/null
+++ b/tools/reduce
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+#!/bin/sh
+
+if [ "$#" -ne 2 ]; then
+    echo "Usage: $0 <init> <expr>"
+    echo ""
+    echo "Run the given command for each newline-separated line in stdin."
+    echo 'The expression computes the next value of "$ACC" (think reduce in many programming languages).'
+    echo 'The initial value of "$ACC" is the first argument to the script.'
+    echo 'The iterator variable is called "$ELEM", and the index variable is called "$IDX".'
+    echo 'The final value of "$ACC" is printed after all lines have been processed.'
+    exit 1
+fi
+
+i=0
+ACC="$1"
+while IFS=$'\n' read -r line; do
+    j=0
+    for item in $line; do
+        eval "X${j}='$item'"
+        j=$((j+1))
+    done
+
+    IDX=$i ELEM="$line" eval "ACC=\"$2\""
+    i=$((i+1))
+done
+
+echo "$ACC"
diff --git a/tools/splitat b/tools/splitat
new file mode 100755
index 0000000..d41521e
--- /dev/null
+++ b/tools/splitat
@@ -0,0 +1,14 @@
+#!/bin/sh
+
+if [ "$#" -ne 1 ]; then
+    echo "Usage: $0 <separator>"
+    echo ""
+    echo "Split the stdin into lines, splitting at the given separator character."
+    exit 1
+fi
+
+while IFS=$'\n' read -r line; do
+    for part in $(echo "$line" | tr "$1" '\n'); do
+        echo "$part"
+    done
+done
diff --git a/tools/words b/tools/words
new file mode 100755
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--- /dev/null
+++ b/tools/words
@@ -0,0 +1,13 @@
+#!/bin/sh
+
+if [ "$#" -ne 0 ]; then
+    echo "Usage: $0"
+    echo ""
+    echo "Echo each whitespace-separated word in stdin on a new line."
+    exit 1
+fi
+
+i=0
+for word in $(cat); do
+    echo "$word"
+done