Add trs(1df)

5 files changed, 62 insertions, 0 deletions

diff --git a/.gitignore b/.gitignore
index 59f79713..e2f5a857 100644
--- a/.gitignore
+++ b/.gitignore
@@ -104,6 +104,7 @@ bin/tl
 bin/tlcs
 bin/tm
 bin/tot
+bin/trs
 bin/try
 bin/u2d
 bin/umake
diff --git a/Makefile b/Makefile
index da41016b..1f620612 100644
--- a/Makefile
+++ b/Makefile
@@ -177,6 +177,7 @@ BINS = bin/ap \
 	bin/tlcs \
 	bin/tm \
 	bin/tot \
+	bin/trs \
 	bin/try \
 	bin/u2d \
 	bin/umake \
diff --git a/README.markdown b/README.markdown
index 1738af22..4cd8ebd0 100644
--- a/README.markdown
+++ b/README.markdown
@@ -532,6 +532,7 @@ Installed by the `install-bin` target:
     to use Taskwarrior, but found it too complex and buggy.
 *   `tm(1df)` runs `tmux(1)` with `attach-session -d` if a session exists, and
     `new-session` if it doesn't.
+*   `trs(1df)` replaces strings (not regular expression) in its input.
 *   `try(1df)` repeats a command up to a given number of times until it
     succeeds, only printing error output if all three attempts failed. Good for
     tolerating blips or temporary failures in `cron(8)` scripts.
diff --git a/bin/trs.awk b/bin/trs.awk
new file mode 100644
index 00000000..5966c520
--- /dev/null
+++ b/bin/trs.awk
@@ -0,0 +1,36 @@
+# Substitute one string for another in input (no regex)
+BEGIN {
+    # Name self
+    self = "trs"
+
+    # No wordsplitting required
+    FS = ""
+
+    # Two and only two arguments required
+    if (ARGC != 3)
+        fail("Need a string and a replacement")
+
+    # Get arguments and blank them so awk doesn't try to read them as files
+    str = ARGV[1]
+    rep = ARGV[2]
+    ARGV[1] = ARGV[2] = ""
+
+    # String length is relevant here
+    if (!(len = length(str)))
+        fail("String to replace cannot be null")
+}
+
+# Bailout function
+function fail(str) {
+    printf "%s: %s\n", self, str | "cat >&2"
+    exit(2)
+}
+
+# Run on each line
+{
+    lin = ""
+    for (buf = $0; ind = index(buf, str); buf = substr(buf, ind + len))
+        lin = lin substr(buf, 1, ind - 1) rep
+    lin = lin buf
+    print lin
+}
diff --git a/man/man1/trs.1df b/man/man1/trs.1df
new file mode 100644
index 00000000..fa5d2d19
--- /dev/null
+++ b/man/man1/trs.1df
@@ -0,0 +1,23 @@
+.TH TRS 1df "May 2017" "Manual page for trs"
+.SH NAME
+.B trs
+\- string version of tr(1)
+.SH SYNOPSIS
+.B trs
+STRING REPLACEMENT
+< file
+.br
+program | 
+.B trs
+STRING REPLACEMENT
+.SH DESCRIPTION
+.B trs
+replaces the string given in its first argument with the string given in its
+second, with no regex metacharacters, in a way that should work on all POSIX
+implementations. It is thereby the string complement for tr(1).
+.P
+The first argument cannot be a null string. The second argument can be blank
+(but must still be specified) to implicitly delete all occurrences of the
+string.
+.SH AUTHOR
+Tom Ryder <tom@sanctum.geek.nz>