commit 1c334e8f893782f590f761f1ec02e110c3981511
parent bf3efc74d7ff94f6be05c5997a50f45e943e86ab
Author: tjg <tjg>
Date: Wed, 19 May 1999 15:10:19 +0000
Documentation: minor fixes to man page.
Diffstat:
| M | rc.1 | | | 49 | ++++++++++++++++++++++++++++++++++++++++++++----- |
1 file changed, 44 insertions(+), 5 deletions(-)
diff --git a/rc.1 b/rc.1
@@ -293,8 +293,9 @@ to run in a protected mode, whereby it becomes more difficult for
an
.I rc
script to be subverted by placing false commands in the environment.
-(Note that this presence of this flag does NOT mean that it is safe to
-run setuid
+(Note that the presence of this flag does
+.I not
+mean that it is safe to run setuid
.I rc
scripts; the usual caveats about the setuid bit still apply.)
.TP
@@ -308,7 +309,7 @@ placed in
.Cr \-V
This flag causes
.I rc
-to print a version string to stdout, and exit immediately.
+to print a version string to standard output, and exit immediately.
.TP
.Cr \-v
This flag causes
@@ -463,6 +464,16 @@ and the standard input may be taken from a file with
.Cr "command < file"
.De
.PP
+Redirections can appear anywhere in the line: the word
+following the redirection symbol is the filename and must be
+quoted if it contains spaces or other special characters.
+These are all equivalent.
+.Ds
+.Cr "echo 1 2 3 > foo"
+.Cr "> foo echo 1 2 3"
+.Cr "echo 1 2 > foo 3"
+.De
+.PP
File descriptors other than 0 and 1 may be specified also.
For example, to redirect standard error to a file, use:
.Ds
@@ -477,6 +488,17 @@ to the same file, use
.Cr "command > file >[2=1]"
.De
.PP
+As in
+.IR sh ,
+redirections are processed from left to right. Thus this sequence
+.Ds
+.Cr "command >[2=1] > file"
+.De
+.PP
+is usually a mistake. It first duplicates standard error to standard
+output; then redirects standard output to a file, leaving standard error
+wherever standard output originally was.
+.PP
To close a file descriptor that may be open, use
.Ci >[ n =]\fR.
For example, to
@@ -485,6 +507,14 @@ close file descriptor 7:
.Cr "command >[7=]"
.De
.PP
+Note that no spaces may appear in these constructs:
+.Ds
+.Cr "command > [2] file"
+.De
+would send the output of the command to a file named
+.Cr [2] ,
+with the intended filename appearing in the command's argument list.
+.PP
In order to place the output of a command at the end of an already
existing file, use:
.Ds
@@ -500,6 +530,12 @@ with the use of
.Cr "command << 'eof-marker'"
.De
.PP
+Subsequent lines form the standard input of
+the command, till a line containing just the
+marker, in this case
+.Cr eof-marker ,
+is encountered.
+.PP
If the end-of-file marker is enclosed in quotes,
then no variable substitution occurs inside the here document.
Otherwise, every variable is substituted
@@ -524,7 +560,7 @@ Additionally,
.I rc
supports ``here strings'', which are like here documents,
except that input is taken directly from a string on the command line.
-Its use is illustrated here:
+Their use is illustrated here:
.Ds
.Cr "cat <<< 'this is a here string' | wc"
.De
@@ -559,6 +595,9 @@ use:
.Cr "command |[2] wc"
.De
.PP
+As with file redirections, no spaces may occur in the construct specifying
+numbered file descriptors.
+.PP
The exit status of a pipeline is considered true if and only if every
command in the pipeline exits true.
.SS "Commands as Arguments"
@@ -579,7 +618,7 @@ does it like this:
.De
.PP
compares the output of the two commands in braces.
-A note: since this form of
+Note: since this form of
redirection is implemented with some kind of pipe, and since one cannot
.IR lseek (2)
on a pipe, commands that use
