initial commit of 'which' utility and help page.

BIN/WHICH.txt

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+NEW
+  PREFIX
+AUTO 4,1
+#!/bin/sh
+#
+# which
+#
+# locates a program in path
+#
+
+set -E
+
+if [ -z $1 ]
+    echo "USAGE: which program ..."
+    exit 120
+fi
+
+set T = "${TEMP}which$$.tmp"
+set A = 0
+set F = 0
+set S = 0
+set L = 1
+
+# get options
+while [ ${L} -eq 1 ]
+    if [ $1 = "-a" ] or [ $1 = "-A" ]
+        set A = 1
+        shift
+    else
+        if [ $1 = "-s" ] or [ $1 = "-S" ]
+            set S = 1
+            shift
+        else
+            set L = 0
+        fi
+    fi
+loop
+
+# split dirs in path
+echo ${PATH} > ${T}
+set L = `sed "s/:/ /" ${T}`
+rm -q -c ${T}*
+
+# find instances
+while [ $# -gt 0 ]
+    set F = ${F} + 1
+    for D in ${L}
+        # check for file
+        if [ ${S} -eq 0 ]
+            ls -f ${D}$1
+            set T = $?
+        else
+            ls -f ${D}$1 > /dev/null
+            set T = $?
+        fi
+
+        # process result
+        if [ ${T} -eq 0 ]
+            set F = ${F} - 1
+            if [ ${A} -eq 0 ]
+                break
+            fi
+        fi
+    next
+    shift
+loop
+
+# -s numeric result
+if [ ${S} -gt 0 ]
+    if [ ${F} -eq 0 ]
+        exit 0
+    else
+        exit 70
+fi
+
+MAN
+TEXT /BIN/which

HELP/which.txt

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+TITLE
+A2osX which (bin/which) Command Help
+
+     which -- locate a program file in the user's path
+
+SYNOPSIS
+     which program ...
+
+DESCRIPTION
+    The which utility takes a list of command names and searches the path for
+    each and will report back which specific executable would have been picked
+    up if the command was actually run.
+
+    The which utility accepts the following options:
+
+    -a          List all instances found instead of just the first one.
+
+    -s          No output, just return 0 if all programs are found, or 1 if
+                some were not found.
+
+PAGE
+EXAMPLES
+    Locate the cp and ls commands:
+
+        # which cp ls
+        /FULL32/bin/cp
+        /FULL32/bin/ls
+
+    Do not show output, just return code:
+
+        # which -s seq
+        # echo $?
+        0
+
+        # which -s fakecmd
+        # echo $?
+        1
+
+
+HISTORY
+    The which command first appeared in FreeBSD 2.1 and was a Perl script
+    written by Wolfram Schneider <wosch@FreeBSD.org>. The A2osX which command
+    was developed by Brian J. Bernstein <brian@dronefone.com> in Dec 2022.
+