Linux Commands

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Revision as of 14:57, 13 October 2008 by Mip (talk | contribs) (→‎sed)
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grep

grep -Rsl PATTERN [FILE]            # Recursive, no error output, only list filename
grep BASIC-REG-EXP-PATTERN [FILE]   # Use classic regexp (like "dma\|DMA")
egrep EXT-REG-EXP-PATTERN [FILE]    # Same as grep -E. Use extended regexp (like "dma|DMA")
fgrep FIXED-STRINGS-REG-EXP [FILE]  # Same as grep -F. Pattern is a list of strings to match.
grep -n PATTERN [FILE]              # Print matched line numbers.
grep -- "-s" [FILE]                 # Search for text "-s"

rpm

rpm -ivh package                    # Installing a package - verbose and progress bars
rpm -iv -nodeps package             # Installing a package (verbose), ignore dependencies
  • Query commands
rpm -ql package                     # List files provided by a package
  • To query a package that has not been installed, add -p option to the command:
rpm -qpl package                    # List files provided by a package

sed

sed [OPTION]... {script-only-if-no-other-script} [input-file]...
sed -n                              # Silent - suppress automatic printing of pattern space
sed -r                              # Use extended regular expression
sed -i "s/foo/bar/" *.txt           # In-place file modification

References

Regular expressions

The information below is only illustrative. See e.g. Wikipedia page for reference information. The list below is actually for extended regular expressions, which can be obtained in sed using option -r (sed -r).

Regexp Description
. Match any character
gray|grey Match gray or grey
gr(a|e)y Match gray or grey
gr[ae]y Match gray or grey
file[^0-2] Match file3 or file4, but not file0, file1, file2.
colou?r (zero or one) - Match Color or Colour.
ab*c (zero or more) - Match ac, abc, abbc, ....
ab+c (one or more) - Match abc, abbc, abbbc, ....
a{3,5} (at least m and not more than n times) - Match aaa, aaaa, aaaaa.
^on single line$ (start and end of line) - Match on single line on a single line.

When using standard (non-extended) regular expression, some special meta-characters (like the parenthesis ( ), or braces { }) must be quoted with backslash \.

Miscellaneous

htop
an improved top command (http://htop.sourceforge.net/index.php)
strace
trace system calls and signals