printf

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طريقة الكتابة

printf [-v VAR] FORMAT [ARGUMENT]...

الأجزاء الرئيسية

%s

Text.

%d, %i

Whole number.

%f, %.2f

Decimal number (with 2 decimals).

%x, %o

Hex / octal.

%5s, %-10s

Width 5 (right aligned) / width 10 left aligned.

%05d

Pad with zeros.

%q

Quote for the shell (bash).

%(FORMAT)T

Date and time (bash), like %(%F)T.

%%

A % sign.

\n, \t, \\

New line, tab, backslash.

الأكثر استخدامًا

لا يوجد شيء يطابق هذا الفلتر.

$ مستخدم عادي# بصلاحية root (أو مع sudo)

1. 1Text with a new line

   $printf "Hello %s\n" "$USER"
   Hello student

   Add \n yourself.

2. 2Aligned columns

   $printf "%-10s %5s\n" USER UID root 0 lisa 1001
   USER         UID
   root           0
   lisa        1001

   The format repeats for each pair.

3. 3Numbers with decimals

   $printf "%.2f GiB\n" 3.14159
   3.14 GiB

   Rounded.

4. 4Leading zeros

   $for i in 1 2 10; do printf "server%02d\n" $i; done
   server01
   server02
   server10

   Names for many hosts.

5. 5Write a file with lines

   $printf 'line1\nline2\n' > /tmp/two-lines.txt

   Safer than echo -e.

6. 6Date without calling date

   $printf '%(%F %T)T\n' -1

   -1 = now (bash builtin).

7. 7Store in a variable

   $printf -v STAMP '%(%Y%m%d)T' -1; echo "backup-$STAMP.tgz"

   No subshell needed.

8. 8Hex of a number

   $printf "%x\n" 255
   ff

   Also %o for octal.

9. 9Quote a value safely for the shell (security)

   $printf '%q\n' "file name; rm -rf /"
   file\ name\;\ rm\ -rf\ /

   Safe to paste into a command.

10. 10A simple table from a file

    $while IFS=: read -r U _ ID _; do printf "%-15s %6d\n" "$U" "$ID"; done < /etc/passwd | head -3

    Neat report.

لا يوجد شيء يطابق هذا الفلتر.

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