math-linux.com

How to Get or Extract filename and extension in bash

Nadir SOUALEM — 2013-03-10T20:00:00Z

nsoualem@gold: -> PICTURE=Tux.jpg
nsoualem@gold: -> echo $PICTURE%%.*
Tux
nsoualem@gold: -> echo $PICTURE#*.
jpg
For multiples extensions files: nsoualem@gold: -> FILE=archive.tar.gz
nsoualem@gold: -> echo $FILE%%.*
archive
nsoualem@gold: -> echo $FILE%.*
archive.tar
nsoualem@gold: -> echo $FILE#*.
tar.gz
nsoualem@gold: -> echo $FILE##*. (...)

- Bash / Bash, filename, extension

RPM What files have been changed ? — Verify System Files

Nadir SOUALEM — 2013-03-10T14:25:04Z

[user@localhost] rpm -Va --nomtime 
 S.5..... c /etc/ssh/sshd_config
 S.5..... c /etc/updatedb.conf

V for verify
a for all packages
nomtime do not care about modification time

The format of the output is a string of 8 characters, a possible attribute marker:

c %config configuration file.
d %doc documentation file.
g %ghost file (i.e. the file contents are not included in the package payload).
l %license license file.
r %readme readme file.

from the package header, followed by the file name. Each of the 8 characters denotes the result of a comparison of attribute(s) of the file to the value of those attribute(s) recorded in the database. A single "." (period) means the test passed, while a single "?" (question mark) indicates the test could not be performed (e.g. file permissions prevent reading). Otherwise, the (mnemonically emBoldened) character denotes failure of the corresponding —verify test:

S file Size differs
M Mode differs (includes permissions and file type)
5 MD5 sum differs
D Device major/minor number mismatch
L readlink(2) path mismatch
U User ownership differs
G Group ownership differs
T mTime differs
P caPabilities differ

Back to previous directory in shell cd,$OLDPWD

Nadir SOUALEM — 2013-03-10T10:18:20Z

"cd -" works, it will call $OLDPWD i.e. pathname of the previous working directory.

- Bash

Error "standard in must be a tty" when doing su - $user

Nadir SOUALEM — 2013-03-10T09:57:29Z

When

su - $user -c "$command" &

gives "standard in must be a tty".

Edit your /etc/sudoers file, by using visudo command:
# visudo
comment out the line "Defaults requiretty".

A most secure way should be to add:

Defaults:[username] !requiretty

How to write table in Latex ? \begin{tabular}...\end{tabular}

Nadir SOUALEM — 2011-06-19T21:37:36Z

Environment

You must use the tabular environment.

Description of columns

Description of the columns is done by the letters r, l or c
r right-justified column
l left-justified column
c centered column

A column can be defined by a vertical separation | or nothing.

When several adjacent columns have the same description, a grouping is possible:

*{nb_columns}{description}

Lines description

\hline provides a horizontal line between two lines
The symbol & separates each column.
The symbol \\ makes a new line
\cline{i-j} horizontal line between columns i and j

Exemple :

\begin{center}
 \begin{tabular}{| l | c || r | }
 \hline
 1 & 2 & 3 \\ \hline
 4 & 5 & 6 \\ \hline
 7 & 8 & 9 \\
 \hline
 \end{tabular}
 \end{center}

\begin{tabular}{|*{2}{c|}l r|}
 \hline
 math & linux & dot & com \\
 center & center& left & right \\
 \hline
 $\sigma$ & $\alpha$ & $\rho$ & $\theta$ \\
 \hline
 \end{tabular}

\begin{tabular}{|r|l|}
 \hline
 2B & hexadecimal \\
 53 & octal \\ \cline{2-2}
 101011 & binary \\
 \hline \hline
 43 & decimal \\
 \hline
 \end{tabular}

Comment faire un tableau en Latex ? \begin{tabular}...\end{tabular}

Nadir SOUALEM — 2011-06-19T13:57:31Z

Environnement

Vous devez utiliser l'environnement tabular.

Description des colonnes

La description des colonnes est faite par les lettres r, l ou c
r colonne de texte justifié à droite
l colonne de texte à gauche
c colonne de texte centré

Une colonne peut être délimitée par une séparation
verticale : | ou rien.

Lorsque plusieurs colonnes voisines possèdent la même description, un regroupement est possible :

*{nb_colonne}{description}

Description des lignes

\hline permet d'obtenir une ligne horizontale entre deux lignes
le symbole & sépare chaque colonne .
le symbole \\ permet un changement de ligne
\cline{i-j} ligne horizontalle entre les colonnes i et j

Exemple :

\begin{center}
 \begin{tabular}{| l | c || r | }
 \hline
 1 & 2 & 3 \\ \hline
 4 & 5 & 6 \\ \hline
 7 & 8 & 9 \\
 \hline
 \end{tabular}
 \end{center}

\begin{tabular}{|*{2}{c|}l r|}
 \hline
 math & linux & dot & com \\
 center & center& left & right \\
 \hline
 $\sigma$ & $\alpha$ & $\rho$ & $\theta$ \\
 \hline
 \end{tabular}

\begin{tabular}{|r|l|}
 \hline
 2B & hexadecimal \\
 53 & octal \\ \cline{2-2}
 101011 & binary \\
 \hline \hline
 43 & decimal \\
 \hline
 \end{tabular}

gcc / g++ how to dump all preprocessor definitions

Nadir SOUALEM — 2011-06-13T08:39:44Z

Compilation option -E -dM gives the result.

g++ -E -dM foo.h

Instead of the normal output, generate
a list of #define directives for all
the macros defined during the
execution of the preprocessor,
including predefined macros. This
gives you a way of finding out what is
predefined in your version of the
preprocessor. Assuming you have no
file foo.h, the command

touch foo.h
 gcc -E -dM foo.h
 #define __DBL_MIN_EXP__ (-1021)
 #define __UINT_LEAST16_MAX__ 65535
 #define __FLT_MIN__ 1.17549435082228750797e-38F
 #define __UINT_LEAST8_TYPE__ unsigned char
 #define __INTMAX_C(c) c ## L
 #define __CHAR_BIT__ 8
 #define __UINT8_MAX__ 255
 #define __WINT_MAX__ 4294967295U
 #define __SIZE_MAX__ 18446744073709551615UL
 #define __WCHAR_MAX__ 2147483647
 #define __GCC_HAVE_SYNC_COMPARE_AND_SWAP_1 1
 #define __GCC_HAVE_SYNC_COMPARE_AND_SWAP_2 1
 #define __GCC_HAVE_SYNC_COMPARE_AND_SWAP_4 1
 #define __DBL_DENORM_MIN__ ((double)4.94065645841246544177e-324L)
 #define __GCC_HAVE_SYNC_COMPARE_AND_SWAP_8 1
 #define __FLT_EVAL_METHOD__ 0
 #define __unix__ 1
 #define __x86_64 1
 #define __UINT_FAST64_MAX__ 18446744073709551615UL
 #define __SIG_ATOMIC_TYPE__ int
 #define __DBL_MIN_10_EXP__ (-307)
 #define __FINITE_MATH_ONLY__ 0
 #define __GNUC_PATCHLEVEL__ 2
 #define __UINT_FAST8_MAX__ 255
 #define __DEC64_MAX_EXP__ 385
 #define __INT8_C(c) c
 #define __UINT_LEAST64_MAX__ 18446744073709551615UL
 #define __SHRT_MAX__ 32767
 #define __LDBL_MAX__ 1.18973149535723176502e+4932L
 #define __UINT_LEAST8_MAX__ 255
 #define __UINTMAX_TYPE__ long unsigned int
 #define __linux 1
 #define __DEC32_EPSILON__ 1E-6DF
 #define __unix 1
 #define __UINT32_MAX__ 4294967295U
 #define __LDBL_MAX_EXP__ 16384
 #define __WINT_MIN__ 0U
 #define __linux__ 1
 #define __SCHAR_MAX__ 127
 #define __WCHAR_MIN__ (-__WCHAR_MAX__ - 1)
 #define __INT64_C(c) c ## L
 #define __DBL_DIG__ 15
 #define _FORTIFY_SOURCE 2
 #define __SIZEOF_INT__ 4
 #define __SIZEOF_POINTER__ 8
 #define __USER_LABEL_PREFIX__ 
 #define __STDC_HOSTED__ 1
 #define __LDBL_HAS_INFINITY__ 1
 #define __FLT_EPSILON__ 1.19209289550781250000e-7F
 #define __LDBL_MIN__ 3.36210314311209350626e-4932L
 #define __DEC32_MAX__ 9.999999E96DF
 #define __INT32_MAX__ 2147483647
 #define __SIZEOF_LONG__ 8
 #define __UINT16_C(c) c
 #define __DECIMAL_DIG__ 21
 #define __gnu_linux__ 1
 #define __LDBL_HAS_QUIET_NAN__ 1
 #define __GNUC__ 4
 #define __MMX__ 1
 #define __FLT_HAS_DENORM__ 1
 #define __SIZEOF_LONG_DOUBLE__ 16
 #define __BIGGEST_ALIGNMENT__ 16
 #define __DBL_MAX__ ((double)1.79769313486231570815e+308L)
 #define __INT_FAST32_MAX__ 9223372036854775807L
 #define __DBL_HAS_INFINITY__ 1
 #define __DEC32_MIN_EXP__ (-94)
 #define __INT_FAST16_TYPE__ long int
 #define __LDBL_HAS_DENORM__ 1
 #define __DEC128_MAX__ 9.999999999999999999999999999999999E6144DL
 #define __INT_LEAST32_MAX__ 2147483647
 #define __DEC32_MIN__ 1E-95DF
 #define __DBL_MAX_EXP__ 1024
 #define __DEC128_EPSILON__ 1E-33DL
 #define __SSE2_MATH__ 1
 #define __PTRDIFF_MAX__ 9223372036854775807L
 #define __amd64 1
 #define __LONG_LONG_MAX__ 9223372036854775807LL
 #define __SIZEOF_SIZE_T__ 8
 #define __SIZEOF_WINT_T__ 4
 #define __GCC_HAVE_DWARF2_CFI_ASM 1
 #define __GXX_ABI_VERSION 1002
 #define __FLT_MIN_EXP__ (-125)
 #define __INT_FAST64_TYPE__ long int
 #define __DBL_MIN__ ((double)2.22507385850720138309e-308L)
 #define __LP64__ 1
 #define __DECIMAL_BID_FORMAT__ 1
 #define __DEC128_MIN__ 1E-6143DL
 #define __REGISTER_PREFIX__ 
 #define __UINT16_MAX__ 65535
 #define __DBL_HAS_DENORM__ 1
 #define __UINT8_TYPE__ unsigned char
 #define __NO_INLINE__ 1
 #define __FLT_MANT_DIG__ 24
 #define __VERSION__ "4.5.2"
 #define __UINT64_C(c) c ## UL
 #define __INT32_C(c) c
 #define __DEC64_EPSILON__ 1E-15DD
 #define __DEC128_MIN_EXP__ (-6142)
 #define __INT_FAST32_TYPE__ long int
 #define __UINT_LEAST16_TYPE__ short unsigned int
 #define unix 1
 #define __INT16_MAX__ 32767
 #define __SIZE_TYPE__ long unsigned int
 #define __UINT64_MAX__ 18446744073709551615UL
 #define __INT8_TYPE__ signed char
 #define __ELF__ 1
 #define __FLT_RADIX__ 2
 #define __INT_LEAST16_TYPE__ short int
 #define __LDBL_EPSILON__ 1.08420217248550443401e-19L
 #define __UINTMAX_C(c) c ## UL
 #define __SSE_MATH__ 1
 #define __k8 1
 #define __SIG_ATOMIC_MAX__ 2147483647
 #define __SIZEOF_PTRDIFF_T__ 8
 #define __x86_64__ 1
 #define __DEC32_SUBNORMAL_MIN__ 0.000001E-95DF
 #define __INT_FAST16_MAX__ 9223372036854775807L
 #define __UINT_FAST32_MAX__ 18446744073709551615UL
 #define __UINT_LEAST64_TYPE__ long unsigned int
 #define __FLT_HAS_QUIET_NAN__ 1
 #define __FLT_MAX_10_EXP__ 38
 #define __LONG_MAX__ 9223372036854775807L
 #define __DEC128_SUBNORMAL_MIN__ 0.000000000000000000000000000000001E-6143DL
 #define __FLT_HAS_INFINITY__ 1
 #define __UINT_FAST16_TYPE__ long unsigned int
 #define __DEC64_MAX__ 9.999999999999999E384DD
 #define __CHAR16_TYPE__ short unsigned int
 #define __PRAGMA_REDEFINE_EXTNAME 1
 #define __INT_LEAST16_MAX__ 32767
 #define __DEC64_MANT_DIG__ 16
 #define __INT64_MAX__ 9223372036854775807L
 #define __UINT_LEAST32_MAX__ 4294967295U
 #define __INT_LEAST64_TYPE__ long int
 #define __INT16_TYPE__ short int
 #define __INT_LEAST8_TYPE__ signed char
 #define __DEC32_MAX_EXP__ 97
 #define __INT_FAST8_MAX__ 127
 #define __INTPTR_MAX__ 9223372036854775807L
 #define linux 1
 #define __SSE2__ 1
 #define __LDBL_MANT_DIG__ 64
 #define __DBL_HAS_QUIET_NAN__ 1
 #define __SIG_ATOMIC_MIN__ (-__SIG_ATOMIC_MAX__ - 1)
 #define __k8__ 1
 #define __INTPTR_TYPE__ long int
 #define __UINT16_TYPE__ short unsigned int
 #define __WCHAR_TYPE__ int
 #define __SIZEOF_FLOAT__ 4
 #define __UINTPTR_MAX__ 18446744073709551615UL
 #define __DEC64_MIN_EXP__ (-382)
 #define __INT_FAST64_MAX__ 9223372036854775807L
 #define __FLT_DIG__ 6
 #define __UINT_FAST64_TYPE__ long unsigned int
 #define __INT_MAX__ 2147483647
 #define __amd64__ 1
 #define __INT64_TYPE__ long int
 #define __FLT_MAX_EXP__ 128
 #define __DBL_MANT_DIG__ 53
 #define __INT_LEAST64_MAX__ 9223372036854775807L
 #define __DEC64_MIN__ 1E-383DD
 #define __WINT_TYPE__ unsigned int
 #define __UINT_LEAST32_TYPE__ unsigned int
 #define __SIZEOF_SHORT__ 2
 #define __SSE__ 1
 #define __LDBL_MIN_EXP__ (-16381)
 #define __INT_LEAST8_MAX__ 127
 #define __SSP__ 1
 #define __LDBL_MAX_10_EXP__ 4932
 #define __DBL_EPSILON__ ((double)2.22044604925031308085e-16L)
 #define _LP64 1
 #define __UINT8_C(c) c
 #define __INT_LEAST32_TYPE__ int
 #define __SIZEOF_WCHAR_T__ 4
 #define __UINT64_TYPE__ long unsigned int
 #define __INT_FAST8_TYPE__ signed char
 #define __DEC_EVAL_METHOD__ 2
 #define __UINT32_C(c) c ## U
 #define __INTMAX_MAX__ 9223372036854775807L
 #define __FLT_DENORM_MIN__ 1.40129846432481707092e-45F
 #define __INT8_MAX__ 127
 #define __UINT_FAST32_TYPE__ long unsigned int
 #define __CHAR32_TYPE__ unsigned int
 #define __FLT_MAX__ 3.40282346638528859812e+38F
 #define __INT32_TYPE__ int
 #define __SIZEOF_DOUBLE__ 8
 #define __FLT_MIN_10_EXP__ (-37)
 #define __INTMAX_TYPE__ long int
 #define __DEC128_MAX_EXP__ 6145
 #define __GNUC_MINOR__ 5
 #define __UINTMAX_MAX__ 18446744073709551615UL
 #define __DEC32_MANT_DIG__ 7
 #define __DBL_MAX_10_EXP__ 308
 #define __LDBL_DENORM_MIN__ 3.64519953188247460253e-4951L
 #define __INT16_C(c) c
 #define __STDC__ 1
 #define __PTRDIFF_TYPE__ long int
 #define __UINT32_TYPE__ unsigned int
 #define __UINTPTR_TYPE__ long unsigned int
 #define __DEC64_SUBNORMAL_MIN__ 0.000000000000001E-383DD
 #define __DEC128_MANT_DIG__ 34
 #define __LDBL_MIN_10_EXP__ (-4931)
 #define __SIZEOF_LONG_LONG__ 8
 #define __LDBL_DIG__ 18
 #define __UINT_FAST16_MAX__ 18446744073709551615UL
 #define __GNUC_GNU_INLINE__ 1
 #define __UINT_FAST8_TYPE__ unsigned char

will show all the predefined macros.

If you use -dM without the -E option,
-dM is interpreted as a synonym for -fdump-rtl-mach

Reference: http://gcc.gnu.org/onlinedocs/gcc/Preprocessor-Options.html#index-dM-953

Undefined Symbol ___gxx_personality_v0

Nadir SOUALEM — 2011-06-13T07:35:57Z

Probably you try to compile a C++ code with gcc instead of g++ gcc test.cpp
Undefined symbols:
"___gxx_personality_v0", referenced from ...
...
Use g++ instead: g++ test.cpp

- FAQ C++ - gcc/g++ / C++, compilation, C, gcc, g++

g++ compilation option -Weffc++

Nadir SOUALEM — 2011-06-12T20:55:26Z

The following -W... options is not affected by -Wall.

-Weffc++ (C++ and Objective-C++ only)
Warn about violations of the following style guidelines from Scott Meyers' Effective C++ book:

Item 11: Define a copy constructor and an assignment operator for classes with dynamically allocated memory.
Item 12: Prefer initialization to assignment in constructors.
Item 14: Make destructors virtual in base classes.
Item 15: Have operator= return a reference to *this.
Item 23: Don't try to return a reference when you must return an object.

Also warn about violations of the following style guidelines from Scott Meyers' More Effective C++ book:

Item 6: Distinguish between prefix and postfix forms of increment and decrement operators.
Item 7: Never overload &&, ||, or ,.

When selecting this option, be aware that the standard library headers do not obey all of these guidelines; use `grep -v' to filter out those warnings.

gcc /g++ Why some variables are not detected as not used during compilation?

Nadir SOUALEM — 2011-06-12T19:07:48Z

In the following example, variable x is not detected as not used #include
int main()
std::vector< double > x;
int k,l;
g++ -Wall test.cpp
test.cpp: In function 'int main()':
test.cpp:6:6: warning: unused variable 'k'
test.cpp:6:8: warning: unused variable 'l'
Actually, warnings are only declared for built in types (bool, int, float, double, etc ...). Compiler can't determine if removing declaration of x would change the behaviour of (...)

- FAQ C++ - gcc/g++ / C++, compilation, C, gcc, g++