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missing newline character in Gilles' edit. Note that it's GNU specific.
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Stéphane Chazelas
Stéphane Chazelas
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Also sed (here using GNU sed syntax) can do the job:

MYPATH=$(printf %s'%s\n' "$MYPATH" | sed ':b;s/:\([^:]*\)\(:.*\):\1/:\1\2/;tb')

this one works well only in case first path is . like in dogbane's example.

In general case you need to add yet another s command:

MYPATH=$(printf %s'%s\n' "$MYPATH" | sed ':b;s/:\([^:]*\)\(:.*\):\1/:\1\2/;tb;s/^\([^:]*\)\(:.*\):\1/:\1\2/')

It works even on such construction:

$ echo "/bin:.:/foo/bar/bin:/usr/bin:/foo/bar/bin:/foo/bar/bin:/bar/bin:/usr/bin:/bin" \
| sed ':b;s/:\([^:]*\)\(:.*\):\1/:\1\2/;tb;s/^\([^:]*\)\(:.*\):\1/\1\2/'

/bin:.:/foo/bar/bin:/usr/bin:/bar/bin

Also sed can do the job:

MYPATH=$(printf %s "$MYPATH" | sed ':b;s/:\([^:]*\)\(:.*\):\1/:\1\2/;tb')

this one works well only in case first path is . like in dogbane's example.

In general case you need to add yet another s command:

MYPATH=$(printf %s "$MYPATH" | sed ':b;s/:\([^:]*\)\(:.*\):\1/:\1\2/;tb;s/^\([^:]*\)\(:.*\):\1/:\1\2/')

It works even on such construction:

$ echo "/bin:.:/foo/bar/bin:/usr/bin:/foo/bar/bin:/foo/bar/bin:/bar/bin:/usr/bin:/bin" \
| sed ':b;s/:\([^:]*\)\(:.*\):\1/:\1\2/;tb;s/^\([^:]*\)\(:.*\):\1/\1\2/'

/bin:.:/foo/bar/bin:/usr/bin:/bar/bin

Also sed (here using GNU sed syntax) can do the job:

MYPATH=$(printf '%s\n' "$MYPATH" | sed ':b;s/:\([^:]*\)\(:.*\):\1/:\1\2/;tb')

this one works well only in case first path is . like in dogbane's example.

In general case you need to add yet another s command:

MYPATH=$(printf '%s\n' "$MYPATH" | sed ':b;s/:\([^:]*\)\(:.*\):\1/:\1\2/;tb;s/^\([^:]*\)\(:.*\):\1/:\1\2/')

It works even on such construction:

$ echo "/bin:.:/foo/bar/bin:/usr/bin:/foo/bar/bin:/foo/bar/bin:/bar/bin:/usr/bin:/bin" \
| sed ':b;s/:\([^:]*\)\(:.*\):\1/:\1\2/;tb;s/^\([^:]*\)\(:.*\):\1/\1\2/'

/bin:.:/foo/bar/bin:/usr/bin:/bar/bin
don't break on spaces and backslashes
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Gilles 'SO- stop being evil'
Gilles 'SO- stop being evil'
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Also sed can do the job:

MYPATH=$(echoprintf $MYPATH%s "$MYPATH" | sed ':b;s/:\([^:]*\)\(:.*\):\1/:\1\2/;tb')

this one works well only in case first path is . like in dogbane's example.

In general case you need to add yet another s command:

MYPATH=$(echoprintf $MYPATH%s "$MYPATH" | sed ':b;s/:\([^:]*\)\(:.*\):\1/:\1\2/;tb;s/^\([^:]*\)\(:.*\):\1/:\1\2/')

It works even on such construction:

$ echo "/bin:.:/foo/bar/bin:/usr/bin:/foo/bar/bin:/foo/bar/bin:/bar/bin:/usr/bin:/bin" \
| sed ':b;s/:\([^:]*\)\(:.*\):\1/:\1\2/;tb;s/^\([^:]*\)\(:.*\):\1/\1\2/'

/bin:.:/foo/bar/bin:/usr/bin:/bar/bin

Also sed can do the job:

MYPATH=$(echo $MYPATH | sed ':b;s/:\([^:]*\)\(:.*\):\1/:\1\2/;tb')

this one works well only in case first path is . like in dogbane's example.

In general case you need to add yet another s command:

MYPATH=$(echo $MYPATH | sed ':b;s/:\([^:]*\)\(:.*\):\1/:\1\2/;tb;s/^\([^:]*\)\(:.*\):\1/:\1\2/')

It works even on such construction:

$ echo "/bin:.:/foo/bar/bin:/usr/bin:/foo/bar/bin:/foo/bar/bin:/bar/bin:/usr/bin:/bin" \
| sed ':b;s/:\([^:]*\)\(:.*\):\1/:\1\2/;tb;s/^\([^:]*\)\(:.*\):\1/\1\2/'

/bin:.:/foo/bar/bin:/usr/bin:/bar/bin

Also sed can do the job:

MYPATH=$(printf %s "$MYPATH" | sed ':b;s/:\([^:]*\)\(:.*\):\1/:\1\2/;tb')

this one works well only in case first path is . like in dogbane's example.

In general case you need to add yet another s command:

MYPATH=$(printf %s "$MYPATH" | sed ':b;s/:\([^:]*\)\(:.*\):\1/:\1\2/;tb;s/^\([^:]*\)\(:.*\):\1/:\1\2/')

It works even on such construction:

$ echo "/bin:.:/foo/bar/bin:/usr/bin:/foo/bar/bin:/foo/bar/bin:/bar/bin:/usr/bin:/bin" \
| sed ':b;s/:\([^:]*\)\(:.*\):\1/:\1\2/;tb;s/^\([^:]*\)\(:.*\):\1/\1\2/'

/bin:.:/foo/bar/bin:/usr/bin:/bar/bin
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rush
rush
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Also sed can do the job:

MYPATH=$(echo $MYPATH | sed ':b;s/:\([^:]*\)\(:.*\):\1/:\1\2/;tb')

this one works well only in case first path is . like in dogbane's example.

In general case you need to add yet another s command:

MYPATH=$(echo $MYPATH | sed ':b;s/:\([^:]*\)\(:.*\):\1/:\1\2/;tb;s/^\([^:]*\)\(:.*\):\1/:\1\2/')

It works even on such construction:

$ echo "/bin:.:/foo/bar/bin:/usr/bin:/foo/bar/bin:/foo/bar/bin:/bar/bin:/usr/bin:/bin" \
| sed ':b;s/:\([^:]*\)\(:.*\):\1/:\1\2/;tb;s/^\([^:]*\)\(:.*\):\1/\1\2/'

/bin:.:/foo/bar/bin:/usr/bin:/bar/bin