Copy (cp) and Move (mv), Auto-Backup

1. Copy, Link, Move
- 1.1. Test Cases
- 1.2. Conditions, with cases
2. references

1 Copy, Link, Move

At small function family to override cp, ln, and mv commands for files which backup previously saved. For example,

$ cp a b

will backup the current copy of b, if it has been backed up. To force the backup, simply precede the command as here:

$ backup file
$ cp copy file

The backup procedure only saves a fresh copy.

The functions here backup the destination file before being overwritten and after the copy or move. Either the first or second backup may be redundant, but again, an unchanged copy is not duplicated in the backup chain. The redundancy, in this case is worth it.

1.1 Test Cases

For starters, the ln command will be left for future development. The cp and mv commands are rarely used with flag arguments, and only expect file and directory arguments.

Therefore possible test cases involve:

cp file file
cp file directory
cp file file ... directory
cp directory directory

and detect these errors

cp file directory file
cp directory file
cp file file ... file
cp arg    # a single arg
cp        # or none

And identical cases for the mv command.

1.2 Conditions, with cases

In those cases where files are the source and a directory is the destination, then each destination file will have to be tested for the presence of a backup.

So, an early function will be is_backedup, and the template we'll call cpmv.

cpmv_test () 
{ 
    set testcpmv.d;
    [[ -d $1 ]] || mkdir $1;
    [[ -f $1/$(today).txt ]] || { 
	ls -lrt > $1/lrt.txt;
	backup $1/lrt.txt;
	ls -al > $1/al.txt;
	backup $1/al.txt;
	ls -l > $1/l.txt;
	backup $1/l.txt;
	ls -l $1 > $1/$(today).txt;
	backup $1/$(today).txt
    };
    for file in $1/*;
    do
	trace_call file $file;
	read a < /dev/tty;
	( cat $file;
	today ) > $(basename $file);
    done;
    cp *.txt $1
}
cpmv_init () 
{ 
    echo WARNING, cp, mv functions assigned;
    cplnmv_doc
}
cplnmv_doc ()
{
    ${*:-open} http://mcgowans.org/marty3/commonplace/20_red/cplnmv.html
}
is_backedup () 
{ 
    trace_call $*;
    [[ -f ${1:-/dev/null} ]] || return 1;
    [[ -f $(dirname $1)/.bak/$(basename $1) ]]
}
cpmv () 
{ 
    : cpmv xx file ... directory;
    : cpmv xx file file;
    : cpmv xx -flag ...;
    trace_call $*;
    case $2 in 
	-*)
	    trace_call COMMAND $*;
	    command $*;
	    return
	;;
    esac;
    eval local destination=\$$#;
    [[ -d $destination ]] && { 
	cpmv_directory $1 $destination ${*:2};
	return
    };
    [[ $# -gt 3 ]] && { 
	error "cpmv file file";
	return 2
    };
    cpmv_backup $*
}
cp () 
{ 
    report_notargcount 2 $# && return 1
    cpmv cp $*
}
mv () 
{
    report_notargcount 2 $# && return 1
    cpmv mv $*
}
cpmv_backup () 
{ 
    : ~ cmmd source resolved/destination;
    trace_call $*;
    is_backedup $3 && backup $3;
    trace_call COMMAND $*;
    command $*;
    is_backedup $3 && backup $3
}
cpmv_directory () 
{ 
    : ~ cmd directory file ... directory;
    local destination=$2;
    trace_call destination: $destination $*;
    for file in ${*:3};
    do
	[[ $file = $destination ]] && break;
	[[ -d $file ]] && continue;
	local bn=$(basename $file);
	cpmv_backup $1 $file $destination/$bn;
    done
}

2 references

commonplace book
see cplnmv_doc above

Copy (cp) and Move (mv), Auto-Backup

Table of Contents

1 Copy, Link, Move

1.1 Test Cases

1.2 Conditions, with cases

2 references