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Diff for /src/usr.bin/mktemp/mktemp.1 between version 1.19 and 1.20

version 1.19, 2001/10/01 17:08:30 version 1.20, 2001/10/11 00:05:55
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 .Os  .Os
 .Sh NAME  .Sh NAME
 .Nm mktemp  .Nm mktemp
 .Nd make temporary file name (unique)  .Nd make temporary filename (unique)
 .Sh SYNOPSIS  .Sh SYNOPSIS
 .Nm mktemp  .Nm mktemp
 .Op Fl dqtu  .Op Fl dqtu
 .Op Fl p Ar directory  .Op Fl p Ar directory
 .Ar template  .Op Ar template
 .Sh DESCRIPTION  .Sh DESCRIPTION
 The  The
 .Nm mktemp  .Nm mktemp
 utility takes the given file name template and overwrites a  utility takes the given filename
 portion of it to create a unique file name.  .Ar template
 The template may be any file name with some number of  and overwrites a portion of it to create a unique filename.
   The
   .Ar template
   may be any filename with some number of
 .Ql X Ns s  .Ql X Ns s
 appended  appended
 to it, for example  to it, for example
 .Pa /tmp/temp.XXXXXXXXXX .  .Pa /tmp/tfile.XXXXXXXXXX .
   If no
   .Ar template
   is specified a default of
   .Pa tmp.XXXXXXXXXX
   is used and the
   .Fl t
   flag is implied (see below).
 .Pp  .Pp
 The trailing  The trailing
 .Ql X Ns s  .Ql X Ns s
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 random letters.  random letters.
 The name chosen depends both on the number of  The name chosen depends both on the number of
 .Ql X Ns s  .Ql X Ns s
 in the template and the number of collisions with pre-existing files.  in the
 The number of unique file names  .Ar template
   and the number of collisions with pre-existing files.
   The number of unique filenames
 .Nm  .Nm
 can return depends on the number of  can return depends on the number of
 .Ql X Ns s  .Ql X Ns s
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 .Pp  .Pp
 If  If
 .Nm  .Nm
 can successfully generate a unique file name, the file (or directory)  can successfully generate a unique filename, the file (or directory)
 is created with file permissions such that it is only readable and writable  is created with file permissions such that it is only readable and writable
 by its owner (unless the  by its owner (unless the
 .Fl u  .Fl u
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 .Nm mktemp  .Nm mktemp
 is provided to allow shell scripts to safely use temporary files.  is provided to allow shell scripts to safely use temporary files.
 Traditionally, many shell scripts take the name of the program with  Traditionally, many shell scripts take the name of the program with
 the PID as a suffix and use that as a temporary file name.  the PID as a suffix and use that as a temporary filename.
 This kind of naming scheme is predictable and the race condition it creates  This kind of naming scheme is predictable and the race condition it creates
 is easy for an attacker to win.  is easy for an attacker to win.
 A safer, though still inferior approach  A safer, though still inferior approach
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 .It Fl p Ar directory  .It Fl p Ar directory
 Use the specified  Use the specified
 .Ar directory  .Ar directory
 as a prefix when generating the temporary file name.  as a prefix when generating the temporary filename.
 The  The
 .Ar directory  .Ar directory
 will be overridden by the user's  will be overridden by the user's
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 This is useful if  This is useful if
 a script does not want error output to go to standard error.  a script does not want error output to go to standard error.
 .It Fl t  .It Fl t
 Generate a temporary file rooted in a temporary directory.  Generate a path rooted in a temporary directory.
 The temporary directory is chosen as follows:  This directory is chosen as follows:
 .Bl -bullet  .Bl -bullet
 .It  .It
 If the user's  If the user's
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 .Pp  .Pp
 In this mode, the  In this mode, the
 .Ar template  .Ar template
 should be a directory component (as opposed to a full path) and thus  (if specified) should be a directory component (as opposed to a full path)
 should not contain any forward slashes.  and thus should not contain any forward slashes.
 .It Fl u  .It Fl u
 Operate in  Operate in
 .Dq unsafe  .Dq unsafe
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 where the script should quit if it cannot get a safe  where the script should quit if it cannot get a safe
 temporary file.  temporary file.
 .Bd -literal -offset indent  .Bd -literal -offset indent
 CMD=`basename $0`  TMPFILE=`mktemp /tmp/example.XXXXXXXXXX` || exit 1
 TMPFILE=`mktemp /tmp/$CMD.XXXXXXXXXX` || exit 1  
 echo "program output" >> $TMPFILE  echo "program output" >> $TMPFILE
 .Ed  .Ed
 .Pp  .Pp
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 .Ev TMPDIR  .Ev TMPDIR
 environment variable can be written as follows.  environment variable can be written as follows.
 .Bd -literal -offset indent  .Bd -literal -offset indent
 CMD=`basename $0`  TMPFILE=`mktemp -t example.XXXXXXXXXX` || exit 1
 TMPFILE=`mktemp -t $CMD.XXXXXXXXXX` || exit 1  
 echo "program output" >> $TMPFILE  echo "program output" >> $TMPFILE
 .Ed  .Ed
 .Pp  .Pp
   This can be further simplified if we don't care about the actual name of
   the temporary file.  In this case the
   .Fl t
   flag is implied.
   .Bd -literal -offset indent
   TMPFILE=`mktemp` || exit 1
   echo "program output" >> $TMPFILE
   .Ed
   .Pp
 In some cases, it may be desirable to use a default temporary directory  In some cases, it may be desirable to use a default temporary directory
 other than  other than
 .Pa /tmp .  .Pa /tmp .
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 .Ev TMPDIR  .Ev TMPDIR
 environment variable specifies otherwise.  environment variable specifies otherwise.
 .Bd -literal -offset indent  .Bd -literal -offset indent
 CMD=`basename $0`  TMPFILE=`mktemp -p /extra/tmp example.XXXXXXXXXX` || exit 1
 TMPFILE=`mktemp -t -p /extra/tmp $CMD.XXXXXXXXXX` || exit 1  
 echo "program output" >> $TMPFILE  echo "program output" >> $TMPFILE
 .Ed  .Ed
 .Pp  .Pp
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 For instance, if we attempt to create two temporary files and  For instance, if we attempt to create two temporary files and
 the second one fails we need to remove the first before exiting.  the second one fails we need to remove the first before exiting.
 .Bd -literal -offset indent  .Bd -literal -offset indent
 CMD=`basename $0`  TMP1=`mktemp -t example.1.XXXXXXXXXX` || exit 1
 TMP1=`mktemp -t $CMD.1.XXXXXXXXXX` || exit 1  TMP2=`mktemp -t example.2.XXXXXXXXXX`
 TMP2=`mktemp -t $CMD.2.XXXXXXXXXX`  
 if [ $? -ne 0 ]; then  if [ $? -ne 0 ]; then
         rm -f $TMP1          rm -f $TMP1
         exit 1          exit 1
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 is unable to create the file.  is unable to create the file.
 In this case you can protect that part of the script thusly.  In this case you can protect that part of the script thusly.
 .Bd -literal -offset indent  .Bd -literal -offset indent
 CMD=`basename $0`  TMPFILE=`mktemp -q -t example.XXXXXXXXXX` && {
 TMPFILE=`mktemp -q -t $CMD.XXXXXXXXXX` && {  
         # Safe to use $TMPFILE in this block          # Safe to use $TMPFILE in this block
         echo data > $TMPFILE          echo data > $TMPFILE
         ...          ...
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